"in + a length of time" is said to have two meanings: before the end of a particular period (i.e., within a period fo time), or at the end of that period. How do we know which applies? Consider, for example, the following:

a. Can we get to the airport in an hour?

b. He can get to the airport in an hour.

c. He learned to swim in two months.

Which sense applies? And why?

  • "at the end of that period", as you differentiate it from the first definition, seems to be a description for a very specific instance of time, rather being about a period or duration. Would you provide an example for this very case? I understand your examples as if they are intended to imply a period of time.
    – Cardinal
    May 14, 2020 at 7:29
  • "He learnt to drive in two months" is given by Oxford Advanced Learner's Dictionary as an example of the "at the end of a period of time" sense.
    – Apollyon
    May 14, 2020 at 7:41
  • hmm, that might be opinion based, I construe the "in an hour", as 59 minutes and 59 seconds regardless. So goes for in a week and in two months. It might be an OCD thing. :embarrassed emoji: Maybe the context or the tone of voice would make me think different. I don't know!
    – Cardinal
    May 14, 2020 at 7:45
  • This question is wrong because 'in' doesn't mean 'before the end of a particular period' or 'within a period of time'. 'In' means 'at the end of' and 'within means before the end of'. "He learned to swim in two months." This sentence means he took the duration of two months to learn swimming. It means he was able to swim at the end of two months from a specific time in the past, NOT before the completion of two months. May 14, 2020 at 11:47
  • Nothing wrong with the question. You might want to read the passage from Longman English Grammar by L. G. Alexander: "In and, more formally, within, sometimes mean 'before the end of a stated period of time, which may be present, past or future: / always eat my breakfast in ten minutes I finished the examination in (within) an hour and a half"
    – Apollyon
    May 14, 2020 at 13:40

1 Answer 1


You're right, both a and b could mean either that the journey could end in one hour from now, or that the journey will take one hour regardless of departure time.

a. Can we get to the airport in an hour?

b. He can get to the airport in an hour.

As in a lot of cases you will come across in English, context is everything. An example of duality of meaning I was taught in school was "my father travels to work in a bowler hat", which could mean he wears a hat while travelling, or that the hat is his vehicle. Obviously, the latter is ridiculous, so you wouldn't think that for a moment in a real situation. Likewise, if either of your two statements were said in a conversation, one would hope that the wider context would make it clear what was meant.

There is no ambiguity in c:

He learned to swim in two months.

Because "learned" is in the past tense, this could only have happened in the past. It cannot mean in two month's time. For this sentence to have the same ambiguity as the previous two it would need to match the tense, ie "he can learn to swim in two months".

  • Could you give an example of a context where those sentences would be interpreted as the journey beginning in an hour? I can't seem to interpret them that way at all. Only as "the journey time is (under) an hour" or "the arrival time could be (less than) an hour from now" (which are essentially the same thing as each other, if you assume the journey can start immediately).
    – Chris H
    May 14, 2020 at 8:27
  • @ChrisH Hi Chris, perhaps this is particular to British English, but we idiomatically use expressions like "I can't get to the shops" to mean that we can't leave the house, or "get to work!" to mean "go to work". Basically, "get to" can mean to start your journey, rather than the end of it. If this isn't the case in American English I can add a disclaimer?
    – Astralbee
    May 14, 2020 at 8:32
  • perhaps regional, but it'd be more specific than that (I'm also British). I'm familiar with "get to work", for example, as an instruction to go to work (right now). But (at least for me) once a time is added, like "get to work in an hour", that unambiguously means being there in an hour.
    – Chris H
    May 14, 2020 at 8:39
  • @Astralbee You are talking about a different kind of ambiguity. I'm asking about "before the end of a particular period (i.e., within a period fo time), and "at the end of that period. "
    – Apollyon
    May 14, 2020 at 8:44
  • 1
    @ChrisH immaterial now as i've edited it out. Apollyon is correct that there are at least 2 possible meanings even if you don't agree with mine!
    – Astralbee
    May 14, 2020 at 9:06

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