means A large ornamental bird, the male of which displays a spectacular fan of iridescent, eye-spotted tail feathers; also used of a vain person who shows off.

from From Old English 'pawa' or 'pea' (the bird), itself borrowed from Latin 'pavo' meaning peacock, plus the English 'cock' for the male bird. The Latin 'pavo' may ultimately echo a Tamil or other South Asian word, fitting since the birds are native to the Indian subcontinent and travelled west through trade. The strutting display gave us the verb 'to peacock,' to show off, by the 19th century.