Oxford Learner's dictionary says, in its definition of on:

5 immediately after something
On arriving home I discovered they had gone.
There was a letter waiting for him on his return.

But I think it's more like 'when' than 'after', isn't it?

What does, for example, "On returning from holidays" mean? After arriving home? Can't this also mean "On the way home" and even "When about to get going home"?

  • 2
    I think, in this case, "on" is being used as if it were "upon".
    – Catija
    Commented Aug 9, 2017 at 18:45
  • It rained (up)on our arrival. Was it already raining when we arrived, or did it start raining soon after we arrived?
    – TimR
    Commented Aug 9, 2017 at 18:53
  • A native speaker from UK was saying "On returning from Rome, he wrote to the ~ (This indicates that he wrote whilst he was in Rome)" forum.wordreference.com/threads/….
    – karlalou
    Commented Aug 9, 2017 at 19:04
  • "Immediately when something" is not meaningful in English. The adverbial is not just after, but immediately after, and it could arguably be at the moment of. The definition is not a monument to clarity, certainly, but dictionaries are notoriously bad references for prepositions, and on, as a part of many phrasal verbs, has a dizzying number of usages. ("When about to get going home" is very poorly constructed, but it can't substitute for on arriving home, which means "At the moment of arriving home".) Commented Aug 9, 2017 at 19:13
  • "On returning from Rome, he wrote to the Italian embassy" means "After he returned from Rome, he wrote to the Italian embassy." He was no longer in Rome. There is not really ambiguity, but imprecision in on returning. The period described by on returning begins with the moment of his return, but has no fixed duration. It means "pretty soon after he got back" in the American idiom. Commented Aug 9, 2017 at 19:22

2 Answers 2


On [some event] is frequently used to add an element of drama to a sentence, to imply that one event happened after another with no time for preparation or thought. As Catija's comment says, "on arriving home" can mean the same as "upon arriving home", which is to say, "at the moment of arrival". Example:

On seeing the roach she grabbed the can of bug spray.

As P.E. Dant's comment points out, it can also be an imprecise statement that means soon after some event, where the exact amount of time is not important:

On their return they found waiting for them a mysterious package addressed simply, 'To the residents of this house'.


I've found an example.

"On opening the box, be prepared for a slight surprise, as the kit has been (...)."

"(up)on handling" or "(up)on delivery" mean "when handling" and "when delivering," and therefore they are ambiguous, needing context to be clear.

"On arriving home, I noticed a new store had been opened nearby" means just before you arrived home. You can say this before actually enter your house. This is not because 'home' means hometown, but because 'on' doesn't have any sense of 'after.'

So, this statement

"On returning from Rome, he wrote to the ~ (This indicates that he wrote whilst he was in Rome)"

is indeed correct. It can mean he wrote when he was about to leave Rome. I do trust this writer's sense of language as much above average.

on the occasion of
(formal) at the time of an important event
on the occasion of his second wedding
from Longman

Synonyms: at the time when, (...)
from WordReference English Thesaurus

More: on
'On' has the sense of 'upon,' 'toward,' 'forward,' 'near,' but not 'after.'

  • 1
    I don't agree that "on" can mean "just before". It either means at the same time, or shortly afterwards. "On arriving home, I noticed that..." would mean that you were on the doorstep when you noticed that the new store. "On returning from Rome, he wrote..." would mean that he wrote very soon after arriving at home.
    – JavaLatte
    Commented Jun 15, 2018 at 2:23
  • And I do not agree with you. :)
    – karlalou
    Commented Jun 16, 2018 at 16:28

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