I've looked through several online dictionaries to ferret out the meaning of "err on the side of" ("err on the side of", what I mean is I'm more concerned with the underlying definition for the stock phrase and all its other derivatives). But alas, all my efforts at understanding the preceding phrase's definition are to no avail, as no online dictionary provides me with an adequate explanation. I have also found meanings of its variations (namely, "err on the side of caution"). Each and every dictionary entry provides a separate explanation for the aforementioned phrase and its derivatives, which seem to be split between a central theme.

Take The Free Dictionary, for example (example sentences are provided by this online dictionary):

Entry 1) err on the side of (something)

To prioritize something, perhaps excessively or unnecessarily. Often used in the phrase "err on the side of caution."

Example sentence: I like to err on the side of caution and always keep some money in my savings account.

Entry 2) err on the side of:

act with a specified bias towards something.

Entry 3) err on the side of (something):

show slightly too much rather than too little of a quality, especially a good one

Example sentence: When I am marking exam papers, I always try to err on the side of generosity (= I give slightly higher marks than the students may deserve).

Side Note: Err is an old-fashioned word meaning ‘make a mistake’.

I have been stuck in a mental slump, attempting to figure out which definition (in the listed dictionary entries) is the one and true underlying definition of said phrase.

  • 15
    Why do you think these definitions disagree? May 21, 2022 at 5:23
  • 8
    Perhaps next you should examine the definitions of "set" to try to identify the "one and true underlying definition" of that word. May 21, 2022 at 5:54
  • 1
    It means the same thing as always round up when speaking of estimates. That's erring on one side instead of the other ("always round down"). May 21, 2022 at 16:21
  • 1
    How does this count as some sort of "idiom"?
    – tchrist
    May 23, 2022 at 13:09
  • 1
    A related and illustrative concept that I came across in an engineering context is "the right way to be wrong" - in the absence of perfection, erring on the side that's less permanent or less damaging is usually the correct imperfection
    – Chris H
    May 23, 2022 at 13:11

7 Answers 7


"Err on the side of" is used in situations where we probably won't be able to do something exactly, and want to know if it's better to have more, or less.

For examples, "cut some wood 8 inches long, erring on the long side" means that if you don't think you can cut it exactly, make it a little longer, since too short will ruin it (or be difficult to fix). "Add a tablespoon of salt, erring on the light side" means if you have any trouble or confusion adding the salt, use less -- more salt will make it taste worse than less.

Grading homework falls into the same category. It isn't very exact. There are often mistakes which could be -1 points, or -2. We're not sure and we want to grade consistently. "Err on the side of generosity" means to subtract the smaller value. "Err on the side of strictness" means to take off the higher value. Of course we could say this in other ways "err on giving more points" is the same thing as the generosity one.

"Err on the side of caution" is an idiom for deliberately doing more to be extra safe. Suppose a firecracker says you need to be 20 feet away and you have a tape measure which could easily do that. You might instead choose to measure 25 feet to "err on the side of caution". Or even though the firecracker doesn't say you need eye protection, you "err on the side of caution" and wear goggles. A similar phrase is "to be on the safe side".

  • 17
    +1. It might be worth adding that, at least as I always took it, the literal meaning of "err on the side of X" is "if you make a mistake, try to make sure that mistake is in the direction of X rather than its opposite." That makes sense in all of your examples.
    – N. Virgo
    May 22, 2022 at 10:12
  • I find your examples at bit confusing. The long side when cutting some wood will depend on where the cut actually lies. Referring to a light side of salt? Lesser? I don't know who the "we" is when you say "we want to grade consistently". "We" = English speakers? If they say to "stand 25 feet away to err on the side of caution" that simply doesn't mean "wear safety glasses" at all. May 23, 2022 at 17:03
  • 2
    The reason for "erring on the light side" with salt is that it's much easier to add more salt than to take it away!!
    – deep64blue
    May 23, 2022 at 19:23
  • @N.Virgo The thing is, not being able to cut exactly 8 inches of wood, and so on, doesn't feel like so much a mistake as expected inexactitude, which is when I think "err on the..." applies. Can you think of a natural-sounding use involving a clear mistake (as in "what's 34 times 87, erring on the high side?" or "take highway 81, erring to the west")? May 23, 2022 at 23:29
  • @OwenReynolds hmm, well, I don't feel hugely enthusiastic about discussing whether cutting not-quite-exactly 8 inches of would would be considered a mistake or not, but to me it doesn't seem an obviously unsuitable word. A much clearer example is the firework one. Standing too far away would be a mistake of little consequence, while standing too close would be an obviously very bad mistake.
    – N. Virgo
    May 23, 2022 at 23:41

All entries are really saying the same thing, though I agree they're not well articulated. I think there's only really one definition.

When tasked with a job whose performance lies on a spectrum with a sweet spot, "err on the side of..." answers the question, "what if I can't hit the sweet spot perfectly?". It says "well, if you're going to err (=make an error, =not hit the spot perfectly), err on the side of (the direction in which an error is preferable to one in the opposite direction). You are concerned more with the direction of the error than its magnitude, because the cost of an error depends heavily on its direction.

When saving money, performance lies on a spectrum that might look like this

<-- Too Little -- Just Right -- Too Much -->

Ideally you want to save just the right amount, the sweet spot in the middle. But since nobody knows exactly what they'll need for the future, you will probably err. You're unlikely to save exactly the amount that you'll need. If you do, is one side better than the other? A reasonable response might be that if you're going to err, it's better to save too much than too little. It's better to err on the side of "too much". For brevity you might name the left side (saving too little) the side of "recklessness" and the right side (saving too much) the side of "caution". "Just Right" is the ideal. But if you're going to err, err on the side of caution.

If you're grading a paper, you ideally want to give the right grade. But what if one situation is open to interpretation? Perhaps the student isn't technically wrong, but it's not the answer you were expecting. What if you can't mark all papers perfectly (without any complaint from the students)?

Then your scale looks like this:

<-- More Generous -- Just Right -- More Strict -->

If you err on the left side (more generous), if in doubt you will grant the point. If you err on the right side (more strict), if in doubt you will deduct the point. You can choose to err on the side of generosity or the side of strictness.

You can use this in any context. Forget about the 3 definitions you saw. You've got an interview tomorrow morning. Ideally you want to arrive just on time. But you might err and not arrive exactly on time due to traffic. Which side should you err on if you're not going to be exactly on time?

<-- Early -- On Time -- Late -->

If they're going to err, most people would rather be too early than too late, so they would "err on the side of early" (the left side). Erring on the side of early means you'll give yourself more time than usual for the journey tomorrow.

You're driving in a foreign country for the first time. You forget what the speed limit on this road is. Ideally you want to drive at the limit, but if you can't because you don't remember what it is, which side would you rather err on? Would you "err on the side of too slow" or "err on the side of too fast"?

  • "When you're tasked with a duty, you run into qualms of making a mistake. You realize it's impossible to avoid mistakes, so you come up with a plan based on practical yet flawed info. Your strategy is "if I'm going to encounter a mistake, I must decide what course of action will have the least amount of errors/risks I'll face. How do I pull it off? Being excessive in action is mostly the best. Sometimes less is good" You choose the safer option to optimize the outcome, essentially. Which option will help me get the job done, that reduces the chances of risk of error ?" Which part is wrong? May 22, 2022 at 6:11
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    Instead of "reducing the chance of error" or achieving the "least amount of errors", focus on the cost of those errors. In the interview scenario, 15 minutes is a bigger error than 10 minutes, but 15 minutes early has a lower cost than 10 minutes late. The cost is different with the direction of the error. Therefore, you're more concerned with the direction (the "side" you err on) than the amount. If the cost were equivalent in direction, you'd be looking at a ± situation and "err on the side of" would not be used at all. You are optimizing for cost.
    – Steven
    May 22, 2022 at 17:12
  • "Excessive in action is mostly the best" and "sometimes less is good". Sure. Or not. Other times "economy of action is the best" and "more is better". The point of "err on the side of" is to indicate which applies in a given situation. These statements are just instances of "preferred erring sides" rather than definitions. If "less is better" then err on the side of less. If more is better, then err on the side of more.
    – Steven
    May 22, 2022 at 17:25
  • So what I'm deducing from your explanations is something to the effect of "the goal is not to focus on the option with the least amount of downsides/errors, but focus on the more effective option that will lead you to your destination. Pick your poison, blue pill or red pill or choose the lesser of the two evils, if you will". I might be wrong as I've only spent a few minutes reading them May 22, 2022 at 17:50
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    In situations where the direction of the error is more important than its size, the goal is to focus on direction instead of size. It's not so much about the destination as it is minimizing the ultimate cost of your error along the way. "If you're going to be wrong, being wrong in this direction is better than being wrong in the other direction". "Pick your poison" implies that both options are equally bad, but this is different because one side is better than the other.
    – Steven
    May 22, 2022 at 17:58

To err is to make a mistake. Let us therefore follow the sequence of relevant subsequent definitions:

to make a mistake
an action, decision, or judgment that produces an unwanted or unintentional result
a decision or opinion about someone or something that you form after thinking carefully

This leads us to recognise that we may err in various ways. A simple example is when choosing between two clearly defined alternatives. It is a bipolar mistake of judgement in choosing a fight with a bear instead of flight. It would be better to opt for the cautious alternative of flight. If there is an error in this choice the effect is less if we flee than it is when we fight. We err on the side of caution.

More generally, we base our judgements on information that is incomplete, flawed or uncertain. For example, an examination may demand essay answers. The examiners often give different grades whose average value determines pass or fail. Statistically, it may be that the average is 50, the pass mark 50, the range of examiners’ grades is from 40 to 60.

What is one to do in such a situation? The mean value is not reliable; the consequences of failure are grave for the candidate; the consequences of passing are small for the institution. The compassionate thing to do is to err on the side of compassion and pass the candidate.

This analysis applies to all your examples.

  • So my current interpretation of the explanation you provided is the following: to err on the side of sth means to "in order to curtail the most possible damage or baleful effects that an impending danger or calamity will wreak, or to ensure things go smoothly with little to no delays, you take the most prudent course of action predicated on practical but flawed information, using extreme safety measures". Please inform me which part of the statement is flawed. May 21, 2022 at 7:50
  • "If one is uncertain, ignorant, or unsure whether their actions are the correct amount to reduce the number of baleful effects or bring about the best outcome (namely, to bring about the least amount of harm or the best possible outcome), one should do more or do less of what is warranted" Is my estimation off the mark? May 21, 2022 at 19:56
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    @xbladefate25 Broadly, I agree with your second comment; you have summarised the essential meaning of my answer. Regarding your first comment, I am also in general agreement but would not use the term “using extreme safety measures”. I might prefer something like “so as to optimise the outcomes”.
    – Anton
    May 21, 2022 at 20:26

If you look at all the examples you have cited above, they all have one thing in common - and that should make the meaning clear.

It shows that there is a risk of making an error of judgement and by "erring on the side of ..." you are trying to minimize that risk by doing more than would generally be required. The thinking here is generally : Better too much than too little

  • 3
    I think some of OP's confusion might be the word "more" as in example #3 (and possibly your "better too much..."). The expression doesn't imply a quantity of anything other than caution. It just means that if we're going to make a mistake, we will try to favor mistakes with the most favorable / least harmful consequences. If we're buying coffees for the office, it's better to buy too many and have leftovers than to not have enough for everyone. If we're measuring medicine, however, it might be better to take too little and reduce the effectiveness, rather than risking a dangerous overdose.
    – A C
    May 21, 2022 at 16:53
  • I don't think it's necessarily the risk. Another factor is the how easy it's to fix the problem when you're wrong. "Better too much than too little" doesn't work when adding salt to a dish. The risk is roughly the same: it doesn't taste right. But "too little" is easily fixed, just taste and add more salt if necessary.
    – MSalters
    May 23, 2022 at 13:59
  • 1
    I don't think this is correct e.g. with the example of salt in the OP erring on the side of caution means out too little salt rather than too much (as it's much easier to add more salt than to take it away!).
    – deep64blue
    May 23, 2022 at 19:26
  • I think we are kind of splitting hairs here. 'to err on the side of caution' is not about too much or too little salt - it's about more caution than less. So 'more caution' may indicate doing something more or doing something less - whatever increases the caution part. In the case of salt it would be less but in case of travel money it would be more. May 24, 2022 at 10:11

I have been stuck in a mental slump, attempting to figure out which definition (in the listed dictionary entries) is the one and true underlying definition of said phrase.

I cannot help being reminded of the question “Who is the one, true god?”

The general guidance in English is that if the word or phrase is different, then they will have different meanings or nuances. The corollary of this is that there are no true synonyms (or, at least, very, very few) in English, and what appears in a dictionary is a close approximation that depends on the context.

As far as context is concerned, its importance cannot be over-estimated.

Moreover, in dictionaries, whilst the words themselves cannot be copyrighted, the explanatory text can. The consequence of this is that entries from two dictionaries cannot be the same.

It follows that any definition found in any reasonable dictionary will differ slightly from others, however, the overall meaning/nuance of the word in question should be conveyed.


Great question, xbladefate25. I don't think the above answers quite nail it. The phrase most closely fits a situation in which you have a choice to make between two options, either one of which may be an error. But since you aren't sure, you make your choice based on the possible downsides--you err on the side of ______.

For example, you were hoping to get to a meeting fifteen minutes early so you could run through your presentation with the equipment available, but you aren't going to get there with enough time to spare unless you drive aggressively and park illegally.

So, foregoing the dry run might be an error if the equipment malfunctions and ruins your presentation leaving you and your family homeless, penniless, and living under a bridge. Or driving aggressively might be an error if you end up killing someone and spending the rest of your life in prison. So you err on the side of caution and drive safely since prison is worse than living under a bridge (and you are a sociopath indifferent to the fact you killed someone).

  • After I wrote the above, I went out to mow the lawn and, as there is nothing like a mindless task for clarifying one's thoughts, I now disagree with my own answer (though not enough to down vote it). "To err on the side of" definitely contains the idea of a continuum and my example is an either...or situation. Better answers were from The_English_Teacher, @Steven, and Owen Reynolds. I'd try to come up with a better example, but I finished cutting the grass. Maybe I'll go cut the neighbor's.
    – CWill
    May 22, 2022 at 18:27

The three entries have essentially the same meaning.

'Err' means to stray, to wander (like a sheep, for example). It carries the idea of a mistake as a secondary meaning based on the aforementioned meaning. Example: "To err is human, to forgive [is] Divine."

'On the side of' means to have a preference for, a tendency towards, to give priority to, to give allegiance to, and so on. Examples: "The Count settled on the side of King Louis, to his later regret." "They set up camp on the side of the river closest to the woods."

Your entry 1 and 2 are quite similar literal meanings and entry 3 is giving a more descriptive idea of how 'err on the side of' is typically used.

To put them all together, 'err on the side of' means to prefer the given side, often in the sense of allowing a safety margin to help ensure the likelihood of that side. It doesn't assume that you are completely committed to going that way, but if you are going to wander in any particular direction, especially if uncertain, then you will most likely go in the given direction on average, versus the opposite side or direction.

'To err on the side of caution' means to prefer caution over recklessness, often taking practical steps to ensure a lower risk. 'To err on the side of generosity' means to prefer generosity over meanness.

An example: Bjorn at last saw the distant outline of the tower, a tall grey shadow in the mist. The path was winding and visibility poor, so he decided to err on the side of safety, walking with his hand on the stone fence to his left rather than the hundred foot drop on his right. [keywords: safety, hand. He's not going to wander in the wrong direction if he sticks to the wall.]

Or a less physical example: Françoise took a sip from her glass, uncertain if the dapper gentleman was in fact her contact or an enemy agent. She decided to err on the side of caution. A mistake now could get herself and many others killed. She smiled and nodded but said nothing. [Keywords: uncertain, caution. She has no clear way forwards so she decides to prefer safety. The opposite might be... She decided to throw caution to the wind and ask him the password.]

  • "You're walking on a winding road that splits into two. You're not sure which fork to take, risky A or riskier B. You're unsure or ignorant of which to take but you know you're not coming out unscathed. You decide to go down risky path A as it has more favorable consequences with the least amount of toll to pay in terms of risks and error. Doing so cuts down on the final costs you'll incur along the way. The goal is to make out it as safe as we can, so you take the less risky path to optimize your odds of survival. If you went with path B, there'd be great hell to pay" Does this example work? May 24, 2022 at 5:23
  • By work I mean does this analogy/example capture the essence of the definition you listed? May 24, 2022 at 5:23
  • @xbladefate25 not exactly - your example misses the idea of wandering. I've added two more examples - let me know if they help. There's something you are unclear on that I'm having trouble pinpointing. Jun 1, 2022 at 4:03
  • @xbladefate25 To be fair, your example almost works, if your example describes 'to err on the side of caution'. If it is 'to err on the side of trouble', that is different. Jun 1, 2022 at 4:24
  • @xbladefate25 Wandering has the sense of ambiguity and lack of clarity, not choosing the clearcut direct straight way. I think that your example having a distinct clear binary choice is probably what concerns me about it, if that makes sense. Shades of grey, not just black and white. Jun 1, 2022 at 4:31

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