The following sentences seem to mean the same. However, "a jiffy" is a short time, but "long" refers to a long time. Why is that? What's the basis for understanding the sentences when the boldfaced words have opposite meanings?

I’ve just got to fetch some books from upstairs - I won’t be a jiffy.

I’ve just got to fetch some books from upstairs - I won’t be long.

  • @BillyKerr The phrase you say is not idiomatic at all and doesn't make sense is the example found in Cambridge Dictionary for "jiffy"
    – Astralbee
    Sep 29 at 10:18
  • @Astralbee - then I suppose I it's because I don't know it, or don't use it. Reminds me of the incorrect "I could care less" and the correct "I couldn't care less" debacle. I just wouldn't say "I won't be a jiffy" when I literally will be a jiffy.
    – Billy Kerr
    Sep 29 at 10:26
  • 1
    As jiffy is an indeterminate short period of time, you can use it just the way you would a minute. "I won't be a minute." No-one is actually going to time you. I often use the 'yonk' in a joking manner - "I haven't seen John in at least a yonk & a half." as though it was a measurable time period. Sep 29 at 10:52
  • @DoneWithThis. - each to their own. LOL;
    – Billy Kerr
    Sep 29 at 14:03

1 Answer 1


They don't mean exactly the same thing.

There are several words and phrases that mean a moment or a very short period of time. Some of these are predominantly British, but among them are 'jiffy', 'mo' (short for 'moment') and 'tick' (like a tick of the clock, a second). Some of these are hyperbole, of course. Saying you "won't be a jiffy" means you will be so fast it won't even be that length of time. These are things you might say if you think the amount of time is negligible, barely noticeable.

Saying you won't be "long" is less hyperbolic. If you won't be a long period of time then you must only intend to be a short period of time. This is something you would more likely say when you expect to be some time, but it will not be excessive.

  • I think the difference between the two expressions is less clear cut than you suggest. Sep 29 at 10:29
  • Wha't being omitted after "be" in the OP example?
    – Apollyon
    Sep 29 at 10:35
  • Nothing is being omitted. You could expand it to "I won't be as long as a jiffy" but no-one actually would. Sep 29 at 10:47
  • "I won't be a jiffy" may mean that it will be done in the blink of an eye OR it will take quite some time (because I don't exactly know where these books are).
    – Graffito
    Sep 29 at 11:11
  • @DoneWithThis. It's hard for someone whose native language isn't English to see why nothing is being omitted there. After all, you could say I am a human being, I'm short, etc., but how can a person be a period of time, literally speaking?
    – Apollyon
    Sep 29 at 11:53

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