“Couple for Two. For two things to be a couple they must be of one general kind, and their number unimportant to the statement made by them. It would be weak to say, ‘He gave me only one, although he took a couple for himself.’ Couple expresses indifference to the exact number, as does several. That is true, even in the phrase, a married couple, for the number is carried in the adjective and needs no emphasis.”
Excerpted from: Bierce, Ambrose. Write it Right: A Little Blacklist of Literary Faults. Mineola, NY: Dover, 2010.