n. 1 a male peafowl, having brilliant plumage and a tail (with eyelike markings) that can be expanded erect in display like a fan. 2 this type of ostentatious display. peacock blue the lustrous greenish blue of a peacock's neck. peacock butterfly a butterfly, Inachis io, with eyelike markings on its wings.
[ ME pecock f. OE pea f. L pavo + COCK(1) ]