What is the difference between instant and instantaneous? Which is correct in this sentence?

It had an almost __ response time.

3 Answers 3


Based on the fact that manufacturers of instant coffee never call it 'instantaneous coffee' I would say that 'instant' modifies a noun referring to a thing, whereas 'instantaneous' modifies a noun referring to an event. Your example falls in a grey area between the two, because the noun 'time' can refer to either the duration before the response occurs or the event of the response's occurrence.


They are nearly identical. Instantaneous focuses more on something occurring in an instant or instantly, whereas instant simply means "immediately".

However, being that both words necessarily involve time, your sentence would be redundant. Might I suggest one of the following:

It had a near zero response time.

It responded (almost) instantly/instantaneously.


"Instantaneous" has significantly more immediacy associated with it than "instant". If you shift them to adverb form, the difference is even more evident. Consider these two sentences:

-- The spark jumped between the two electrodes instantaneously.

-- Upon receiving news of a moose down by the swamp, the hunter set off immediately.

  • 2
    It would be easier to understand the comparison if the second example used the adverb form of instant rather than immediate. Dec 19, 2021 at 22:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.