"clasp, button, etc. used to secure the cock of a hat," hence "any knot or badge worn on a hat," especially as a sign of political adherence, 1709, earlier cockard (1650s), from French cocarde (16c.), fem. of cocard (Old French cocart) "foolishly proud, cocky," as a noun, "idiot, fool;" an allusive extension from coq (see cock (n.1)).
Cochin-china
cochineal
Cochise
cochlea
cock
cockade
cock-a-doodle-doo
Cockaigne
cockamamie
cockatoo
cockatrice