winnow

verb

• 1 [with object] blow a current of air through (grain) in order to remove the chaff: a combine cuts, threshes, and winnows the grain in one operation
• remove (chaff) from grain:women winnow the chaff from piles of unhusked rice

• 2remove (people or things) from a group until only the best ones are left:guidelines that would help winnow out those not fit to be soldiers
• find or identify (a valuable or useful part of something):amidst this welter of confusing signals, it’s difficult to winnow out the truth

• 3 [no object] literary (of the wind) blow:the autumn wind winnowing its way through the grass
• [with object] (of a bird) fan (the air) with its wings: the emperors of the sky winnowing the air