adj. 25B6; adjective
he was nimble on his feet : AGILE, sprightly, light, spry, lively, quick, graceful, lithe, limber; skilful, deft, dextrous, adroit; informal nippy, twinkle-toed; poetic/literary lightsome.
a nimble mind : QUICK-WITTED, quick, alert, lively, wide awake, observant, astute, perceptive, penetrating, discerning, shrewd, sharp; intelligent, bright, smart, clever, brilliant; informal brainy, quick on the uptake.
clumsy, dull.