Oh dear, can’t resist it when a linguistic matter comes up.
Everybody has been right. As Philip observed, a couple is essentially 2. Technically speaking it is two things bonded together. Couple comes from the Latin ‘copula’ to bond from which we get copulate etc. As a verb, it definitely means that. We couple
together two railway carriages.
Martin, however, is also right. Much as boring linguists like me might mourn the loss of specificity in much modern usage, we must now admit that in common usage couple has also now come to mean a small, vague number, not always easily distinguished from
‘few’ and its allies.
Here I am with Philip. If there are two ducks it is easier to say 2 (fewer keytrokes as Philip noted) . If I try to be brutally honest, I would have to admit that if I said ‘There were a couple of birds in the pond’, I might just as easily have said several
birds or a few birds.
In a heated family argument a couple of weeks ago – or do I mean a few weeks? - it was concluded by a narrow majority that a couple is mostly 2 and if not it should be, that several is three, a few is four, some is more than 4 and ‘a number of’ is more
than that but it depends on the context. Linguist or not, I begged to differ. What is the difference, I said, between ‘a couple of drops of rain’ , ’several drops of rain’, a few drops of rain’ etc. None I say. They are all vague and mean 'not many' but a
couple of drops of rain is a far larger number than a couple of ducks.
Shut up, John, you have said enough.