buzzard n.

c. 1300, "type of hawk not used in falconry," from Old French buisart "harrier, inferior hawk," from buson, buison, apparently from Latin buteonem (nominative buteo) a kind of hawk ("but the process of formation is not evident" - OED), perhaps with -art suffix for one that carries on some action or possesses some quality, with derogatory connotation (see -ard). In the New World the word was extended to the American vulture (by 1830s). De Vaan says buteo is "Probably onomatopoeic, rendering the call of a hawk or buzzard."