Please show me the meanings,when to use and can it be allowed to misuse these two ? (Also greetings from VietNam!)

1 Answer 1


They are completely different. For once means for this one time. Typically it's used when something is an exception to the norm; it doesn't necessarily mean that the event being described is unique.

Say if I am habitually late to the office, but one day manage to make it in at 8 am on the dot. My colleague might remark:

Well, Verbose, you're on time for once!

This doesn't mean I have never been on time before or will never be on time in future; it simply means that my being on time is a rare event, and can in some exaggerated sense be considered unique.

At once means immediately:

Come here at once!
When I heard the good news, I called to congratulate her at once.

There is no overlap in meaning between the two phrases.

  • 1
    You've missed an opportunity to illustrate the two idioms with the same formulation: Verbose, clean up your mess at once/for once! But still worthy of an upvote.
    – deadrat
    Feb 6, 2017 at 8:38
  • 1
    @deadrat Or I could have brought you into the conversation with "Get rid of this dead rat at once!" 😀
    – verbose
    Feb 7, 2017 at 0:50

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