Here is a question by Cardinal from ELL (reproduced below). Although it already has an answer, I am looking for more detail, specifically about the differences in the causal and temporal meanings of 'since', and how they came about.

The definitions for since are:

  1. In the intervening period between (the time mentioned) and the time under consideration, typically the present.
  2. For the reason that; because.

Note the difference in 'a period of time' and 'because'.


  • How did these two meanings develop?

Related question: How do I ensure "since" takes the meaning I want?, which doesn't cover etymology, rather avoiding confusion.

If you would like to discuss this, there is a meta post.

  • 2
    The conflation of ‘since [a point in time]’ and ‘since [a reason is the case]’ is not at all limited to English. It is, in fact, a very common cross-linguistic phenomenon to use a word that refers to a point later in time than another as the basis of a word that refers to the result of a reason. Irish ó and Japanese から -kara also mean both ‘since’ and ‘because’ (and ‘from’); French depuis (time) and puisque (reason) are both based on puis (from a Vulgar Latin comparative of post, i.e., ‘later’); Greek αφού (reason) is from ἀπὸ οὗ ‘from that’; etc. So why? Because language. Jul 2, 2017 at 10:12
  • Comments are not for extended discussion; this conversation has been moved to chat.
    – tchrist
    Jul 6, 2017 at 1:40
  • 1
    Possible duplicate of How do I ensure "since" takes the meaning I want?
    – NVZ
    Jul 6, 2017 at 12:25

3 Answers 3


The OP says, "I am looking for more detail, specifically about the differences in the causal and temporal meanings of 'since', and how they came about," or how the two meanings of since developed.

First, in brief, since has been around a long time, in both senses. The OED includes definitions and quotations relating to each from Middle English sithen, an adverb, preposition, and conjunction:

Forms: α. OE sioððan, OE–ME siððan, ME siððon, ME siððen; OE siðþan, siþþan, siþþon, ME siþþen (ME Orm. siþþenn), ME siþthen, ME sythethyn, sitthen; ME siðen (ME siden, syden), ME siþen (ME siþan), ME syþen, ME siþin; ME–16, 18 sithen (ME sithenne, sithin, sithyn, sithun, 16 sithene); ME–15 sythen (ME sythene, sythin, sythinne, sythyn, sython, sythun). β. OE–ME seoððan, ME seoð-, seodþen ( soððen); OE seoþðan, ME seod-, ME seoðþan; OE seoþþan, ME seoþþen (ME soþþen); ME seððan, ME seððen (ME sed-), ME seþþen; OE seoðan, ME seoðen, seoþen; ME seðen, ME seiþin, ME seþen, seþin; ME–15 sethen (ME sethenne), ME sethyn, ME–15 sethin (ME sethinne, sethun). γ. OE syð-, ME sydþan, OE–ME syþðan, syððan (ME syððon), ME suððen (ME suden), ME swo-, swu-, souððen; OE syþþan ( syþan), ME suþþen, sut(t)hen.

Etymology: Old English siþþon, siþþan, etc. (see above), for earlier *síð þon (þan) ‘subsequent to that’ (compare æfter þon, and German seitdem), with shortening of the first vowel. The Middle English siþen, sithen, however, may also represent Old Norse síðan (Danish siden), of the same meaning.(Show Less) Obs.

There are far more definitions relating to time than to causality.

Under sithens the OED lists one definition as a conjunction:

2a. Seeing that; = sith adv. 2. Now arch.Very common from c1550 to c1650.

1377 Langland Piers Plowman B. xix. 15 Why calle ȝe hym cryst,..sithenes iuwes calle hym ihesus?

1898 E. W. Hamilton Mawkin of Flow xiii It's our plain duty to bide by it, sithens we was sent by Buccleuch to be guided by the hound.

One definition of since from the OED is:

II 4a. Because that; seeing that; inasmuch as. 1577 B. Googe tr. C. Heresbach Foure Bks. Husbandry i. f. 7v Sins it is not yet dinner tyme, let vs walke about.

Turning to time, one OED definition (under B, preposition) is:

Definitions under B (preposition) include:

  1. Ever or continuously from (a specified time, etc.) till now.

1734 tr. C. Rollin Anc. Hist. I. 255 It was now five months and a half since his first setting out.

1780 Mirror No. 103 I inherited a law-suit, kept alive by various means, ever since the year thirty~three.

1861 Thackeray Four Georges iv. 168 He sleeps since thirty years.

This last--"he sleeps since thirty years"--would be an error today, and is the mistake most common among English language learners.

Native English speakers do not have a problem figuring out which meaning of since is meant, and @Clare's point that only sentences in isolation are likely to be confused is one with which I agree. But it's possible to write sentences likely to be confusing to readers, who have to backtrack to figure out what is meant. The solution is to recast (rewrite) a sentence that can be misunderstood.

That said, the best discussion of since I've found is from English Grammar Today:since

We use since as a preposition, a conjunction and an adverb to refer to a time, and as a conjunction to introduce a reason. Since: time We use since to refer back to a previous point in time. We use since as a preposition with a date, a time or a noun phrase: It was the band’s first live performance since May 1990. (since + date) I have been happily married for 26 years, since the age of 21. (since + noun phrase) We also use since as a conjunction to introduce a subordinate clause: It’s so long since I saw them. (since + clause) Lenny had slept most of the way since leaving Texas. (since + clause) He’s been back to the office a few times since he retired. (since + clause)
Since and tenses

When since introduces an action or event at a point of time in the past, we can use the past simple or present perfect after since and the present perfect in the main clause:

They haven’t received any junk mail since they moved house.

They haven’t received any junk mail since they’ve moved house.

We can use the past simple, present perfect or past perfect after since with the expression it + be + time + since:

It’s been years since I rode a bike. (it’s = it has)

It’s been years since I’ve ridden a bike. (it’s = it has)

It’s years since I rode a bike. (it’s = it is)

It’s years since I’ve ridden a bike. (it’s = it is)

It’d been years since I’d ridden a bike. (it’d = it had)

It’s been years since … is more common in American English than It’s years since …. When since introduces a state in the past that is still continuing in the present, we use a present perfect form of the verb after since and a present perfect form of the verb in the main clause:

Since I’ve been back at work, I’ve been feeling great.

Since + -ing

We can use since + -ing form to refer to time when the subject of the verb is the same in the main clause and the subordinate clause:

Since leaving school, he has had three or four temporary jobs. (Since he left school, he has …)

Since moving from a Chicago suburb to southern California a few months ago, I’ve learned how to play a new game called Lanesmanship. (Since I moved …, I’ve learned …) Since, since then

We can use since or since then as an adverb of time when the time reference is understood from the context:

His father doesn’t talk to him. They had an argument a couple of years ago and they haven’t spoken since. (since they had the argument)

They bought the house in 2006 and they’ve done a lot of work on it since then. (since 2006)

We use ever since as a stronger form of since or since then:

When I was young, I had a little collie dog, but one day he bit me really badly. I’ve hated dogs ever since. Since: reason

We use since as a subordinating conjunction to introduce a subordinate clause. We use it to give a reason for something:

Sean had no reason to take a taxi since his flat was near enough to walk to.

Since her husband hated holidays so much, she decided to go on her own.

They couldn’t deliver the parcel since no one was there to answer the door.

Since: typical errors

• We don’t use since with extended periods of time. We use for:

She was waiting for four hours.

Not: She was waiting since four hours.

• We use since, not from, with a clause referring back to a point in time:

I’ve been swimming since I was three years old.

I’ve been swimming from the age of three.

Not: I’ve been swimming from I was three years old.

• We use since, not once, to introduce a reason:

I think I should have my money back since I didn’t have what was promised in the brochure.

Not: I think I should have my money back once I didn’t have …

• We use since, not ago, after ‘it’s a long time’ when we refer back to a point in time:

It’s a long time since your last letter.

Not: It’s a long time ago your last letter.

In summary, the evidence suggests that the two main senses of since developed concurrently, and it's a word easy for non-native speakers to misuse.


Just a note on the present perfect in since-clauses.

The present perfect establishes a terminus ad quem. It looks back over its shoulder at the past, so to speak, and says: as of this moment such-and-such state obtains:

I have eaten seal-meat.

The present perfect does not establish a terminus post quem.

Ever since I have eaten seal meat ... ungrammatical

We would say rather Ever since I ate seal-meat... to establish a point-in-time to serve as a terminus post quem.

(Ever) Since I have seen his first film, I have been following that director. ungrammatical as temporal

(Ever) Since I saw his first film, I have been following that director.

So, when you see the present perfect in the since-clause, since will be causative, not temporal:

Since I have eaten seal-meat, I know what it tastes like.

(Ever) Since I have eaten seal-meat I have known what it tastes like. ungrammatical

  • -1 because (Ever) since I've moved to Boston I've been a Patriots fan: these kind of sentences are grammatical. Jul 2, 2017 at 20:22
  • @Clare.We disagree on this. Can you cite some attestations? Would you say "Ever since I have seen the Empire State Building, I've wanted to move to New York?" books.google.com/ngrams/…
    – TimR
    Jul 3, 2017 at 10:43

Confusion about whether 'since' has been used in a causal or a temporal sense can arise only when the tenses are in agreement so that a temporal meaning can be grammatically assumed:

He has been moody since he lost his job.

She has tried to improve her English since she joined ELU.

There is no ambiguity when sentences are constructed to avoid this arrangement; then 'since' can only be causal, as in the following example;

He is moody, since he has lost his job.

She wants to improve her English, since she is going to join ELU.

If the sentence structure is to be retained then I would certainly advise a Learner to substitute 'because' for 'since', to remove ambiguity.

He has been moody because he lost his job.

She has been trying to improve her English, because she has joined ELU.

Note: this answer specifically addresses the first question originally raised by OP:

How can one avoid such confusion/ambiguity in the use of 'since' (I paraphrase, because OP has now removed this question.)

Note 2: OP has since edited to focus solely on this (originally second) question:

How did these two meanings develop?

This happened since I prepared this answer (but before I could post it) -- however I am not changing my answer since I have no answer to OP's revised question, because I am neither an etymologist nor a linguist.

  • 1
    What about the etymology of why 'since' has these constructions? Jul 1, 2017 at 21:22
  • As I stated in note 2, I know nothing about that 'why', (because I am neither an etymologist nor a linguist) but I am sure somebody at ELU can tell you why, because we have many genuine experts here! Jul 1, 2017 at 21:23
  • In which case, this is a perfect answer to the question everyone thinks this is a duplicate of :) Jul 1, 2017 at 21:25
  • It was a duplicate with a 'why' added; then it became a question of 'why' alone, and that might save it from being closed as duplicate. It is a good question because we don't think 'why' about these grammar things as often as we should, so this is the type of thinking we need more of at EL and U. Jul 1, 2017 at 21:28
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    @English Student I concur. Your program, however, means in effect forbidding the Learner to answer most questions on exams; and although I am of the firm opinion that most exam questions should not be asked, much less answered, the Learner may not enjoy the resulting marks. Jul 1, 2017 at 22:53

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