The Collaborative International Dictionary of English v.0.48:
Couple \Cou"ple\ (k[u^]p"'l), n. [F. couple, fr. L. copula a
bond, band; co- + apere, aptum, to join. See Art, a., and
1. That which joins or links two things together; a bond or
tie; a coupler. [Obs.]
It is in some sort with friends as it is with dogs
in couples; they should be of the same size and
I'll go in couples with her. --Shak.
2. Two of the same kind connected or considered together; a
pair; a brace. "A couple of shepherds." --Sir P. Sidney.
"A couple of drops" --Addison. "A couple of miles."
--Dickens. "A couple of weeks." --Carlyle.
Adding one to one we have the complex idea of a
[Ziba] met him with a couple of asses saddled. --2
Sam. xvi. 1.
3. A male and female associated together; esp., a man and
woman who are married or betrothed.
Such were our couple, man and wife. --Lloyd.
Fair couple linked in happy, nuptial league.
4. (Arch.) See Couple-close.
5. (Elec.) One of the pairs of plates of two metals which
compose a voltaic battery; -- called a voltaic couple or
6. (Mech.) Two rotations, movements, etc., which are equal in
amount but opposite in direction, and acting along
parallel lines or around parallel axes.
Note: The effect of a couple of forces is to produce a
rotation. A couple of rotations is equivalent to a
motion of translation.