I'm seeing the use of "random" instead of "arbitrary", etc., with increasing frequency. To me, "random" has a specific meaning and is not synonymous with these other words.
Is it correct to use it in this way?


4 Answers 4


The definition of arbitrary does include a link with random:

existing or coming about seemingly at random or by chance or as a capricious and unreasonable act of will.

It is reflected by the usage "at random" (by chance), which is valid.
The problem is, random is with other interpretations of the word "random":

Less widely accepted are a couple of slangy uses of the word, mostly by young people.

  • In the first, “random” means “unknown,” “unidentified” as in “some random guy told me at the party that I reminded him of his old girlfriend.”
  • The other is to use random to mean “weird,” “strange,” as in “The party at Jessica’s was so random, not what I was expecting at all!”
    Evidently in this expression randomness is being narrowed down to unlikelihood and that is in turn being connected with strangeness, though randomness in real life is usually quite ordinary and boring.

Use of either of these two expressions in formal speech or writing is likely to annoy or confuse your audience.

  • Common Errors is one of my favorite sites! I didn't even think about looking there for this. Aug 14, 2010 at 23:53
  • Just to add a bit of other info: the OED traces random with the meaning "Peculiar, strange; nonsensical, unpredictable, or inexplicable; unexpected" back to 1970s US computing slang. Anecdotally, I can remember random meaning strange or unexpected being quite common among American teenagers in the early 90s.
    – Kosmonaut
    Mar 11, 2013 at 13:54

I typically use arbitrary when discussing planning or decision-making, or with respect to preference:

"Your choice of shade of blue for that chair seems arbitrary"

and random in cases where selection or ordering are the relevant aspect, or in mathematical or computer programming contexts:

"I'll shuffle these cards to put them in a random order"

That said, I don't think it's necessarily incorrect to use them interchangeably in some cases; it depends on the context:

"I don't find the placement of these tchotchkes as pleasing when they are strewn about in such an arbitrary fashion"


"I don't find the placement of these tchotchkes as pleasing when they are strewn about in such a random fashion"

Even in this case, for myself, the meaning of those two sentences has a slightly different color, but in essense they are interchangeable.

  • 2
    Yes, what context? That is the question. The examples you gave are presumably the specific meaning mentioned in the question. Aug 14, 2010 at 21:36
  • I'm not sure what you're saying, ShreevatsaR, but I was attempting to use an example context for each meaning, since Dennis didn't give us any context to go on.
    – cori
    Aug 14, 2010 at 23:58
  • 1
    You could improve your answer by giving contexts where it is correct to interchange the two words. Aug 15, 2010 at 2:53
  • +1 Your example is an excellent one. I find that to be an acceptable interchange, but it's not the type I was asking about. It's one I hadn't considered though. "Haphazard" would work here, too. Aug 15, 2010 at 15:45

The difference becomes clearer when you consider the meaning of the word arbitrary.

Arbitrary, means something reached through the process of arbitration. An arbitration is the process of reaching a decision between two or more opinions or parties.

While a random sequence has no defined structure or pattern, an arbitrary one does. Random is the result of pure chance – like when we throw a dice – while arbitrary is a result of choice, deliberation, and often negotiations, sometimes extensive ones.

A random sequence of numbers is never wrong, while an arbitrary one can be. Whichever opinion underpins an arbitrary sequence or system, you will need to follow that sequence in order to get it right – whether you agree with the underpinning opinions or not.

A random sequence of numbers could be made into an arbitrary one – by choosing a sequence of random numbers, and making them “right” and thereby any other combination “wrong”. This is exactly what we do when we create a password, or a combination of numbers for opening a safe. They may start as random, but once we have chosen them, they become arbitrary.

  • 3
    I disagree with your definition of "arbitrary" and thus most of the argument in your answer. See the definition at Merriam-Webster. Mar 11, 2013 at 11:09

Here are some examples of the correct usage of random:

  • A random sample of doctors from around the country were selected for the study.
  • We tasted the wines in random order and then rated each.
  • Pick a word at random from the page.
  • The computer program generates a list of random numbers.

Random does not mean arbitrary, strange, unknown or unidentified--no matter how many times adolescents use it that way and no matter how many times you hear it used that way in TV shows and movies. That usage of random is as incorrect as the grammar in the phrase "between you and I" often heard in TV and movies. (I'll bet many people reading this believe "between you and I" is grammatically correct.)

If you meet a stranger on the street, the mere fact that he's a stranger to you does not make him a random person unless he was selected at random to meet you. It's possible that you had chance meeting, but that does not mean the stranger is a random person.

If I make an arbitrary choice, it's possible that I made it randomly, or I might have made it according to my own tastes or preference. But neither usage of arbitrary makes it a synonym or random.


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