I came across this dialogue between two members on here:

A: Are you under 30? [...]

B: I'm just on the cusp of being under 30 so [...]

This got me confused because it's unclear if the person is almost 30 or a little over 30.

I've also asked around and got mixed answers from native speakers -- some say under, some say over.

So I'd like to know what people on here think.

Could you please explain what the expresion means?

How is it different from just "on the cusp of being 30" ?

And because there are different opinions, is there any chance it is intended to be ambiguous?

Thank you!

  • 1
    Seems like a misunderstanding of the meaning of 'cusp', or a joke (e.g. they are actually over 30). The joke would be that normally 'cusps' happen just before something. Commented Apr 28, 2021 at 7:28
  • What @MichaelHarvey said - except I doubt there's any "misunderstanding". B is just facetiously reversing the normal meaning of on the cusp (just before something significant happens) to have it "mean" just after it happened. Commented Apr 28, 2021 at 13:55
  • 1
    It's a joke.
    – Lambie
    Commented Apr 28, 2021 at 15:12
  • @Lambie - yes. to be on the cusp of something is to be on the verge of, or in transition to, that thing, e.g. adulthood, middle age, etc. You can't be on the cusp of 'being under 30' without travelling backwards in time. Commented Apr 29, 2021 at 7:04

2 Answers 2


You'd have to have more to go on that just the snippet in question, but given the odd phrasing, being "on the cusp" is more commonly used when just approaching something I'd suspect self-deprecating humour was being used.

A literal reading of being on the cusp of being under 30 would mean being "very close" to being "under 30" so, perhaps actually 30 or 31 years of age.

That being said, an odd phrasing like this might be more common in a humorous or sarcastic comment allowing the ambiguity of "on the cusp" to cover a more significant misdirection. I wouldn't be surprised to discover that the user in question was closer to 40 than 30.


The "cusp" is the dividing line between two things. "On the cusp" means you are at the point at which you are about to cross over from one thing to another - in your example, from their twenties to their thirties. I understand it to mean they are in their very late twenties - most likely 29.

It is slightly unusual to say you are on the cusp of not being something (ie not being thirty) - it is normally used in a positive sense (eg "I'm on the cusp of my thirties"). However, it is being used slightly humorously in your example, as the person has been asked if they are "under 30". A more likely, real-life response to that would be "only just!"

  • Or, with the same meaning, "Almost." Commented Apr 28, 2021 at 8:20
  • 1
    I think "not quite" would be a more literal reading of this phrase, rather than "only just".
    – Jontia
    Commented Apr 28, 2021 at 13:35

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