If I say "She is seventeen", is it as correct as "She is seventeen year old"?

I know it's correct, because it's used, but are both as correct or the first one is only tolerated?

When did this structure appeared in English? Relatively recently?

I guess y.o is only an abbreviation, and won't be considered as correct.

  • 2
    No - She is seventeen year old is not correct. Valid alternatives are She is a seventeen year old or She is seventeen years old. Note that in the first of those, the noun phrase would normally be hyphenated as seventeen-year-old, but that's just orthography, not real "grammar". May 10, 2017 at 16:09
  • @Fumble - I had the same concern. The O.P.'s title says "years old", but the example says "year old". I'm wondering if that's just a typo.
    – J.R.
    May 10, 2017 at 16:10
  • Typo from someone who don't speak English as her first language.
    – Quidam
    May 10, 2017 at 16:11
  • @J.R.: I didn't notice that, but I guess y.o is only an abbreviation didn't exactly endear me to the question, so I can't be bothered to look for an earlier duplicate (which I've no doubt will exist). May 10, 2017 at 16:12

2 Answers 2


"She is seventeen" and "She is seventeen years old" are both equivalent ways of saying that she is seventeen years of age - note the "s" after years. In regards the first expression, the fact that it refers to age is implied and commonly accepted.

I would not say that that the first one is merely "tolerated" - that's a bit of a strange word to use there. I would say that it is more informal than the second one.

I don't know when this structure - assuming you mean the first - appeared, but it is definitely still used today, if that's your concern.

y.o. is definitely an abbreviation, and one that I have never seen or heard before, until I read your question. So, it's not something used by native speakers.


In general with times and ages, if a number clearly indicates what it is counting, it is not necessary to include that information.

If I say she was just seventeen, you know what I mean (from "I saw her standing there" by The Beatles) it is very clear I mean her age, in years. It is unlike I mean her weight in kilo's or stones or her height in meters or feet.

In the same way, you can leave out "o'clock" and the likes when you say I got up at three this morning. Obviously that means oh-three-hundred hours, 03:00h AM or three o'clock in the morning.

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