to remove waste matter from (grain) by exposure to a current of air
to remove (waste matter) from grain in this way
(often + out) to separate or select (the most valuable things or people) from a mass or group
(often + out) to get rid of (something undesirable or unwanted things or people)
literary said of the wind: to blow on (something)
the wind winnowing his thin white hair — Time
to separate chaff from grain by exposure to a current of air
to separate desirable and undesirable elements
winnower noun
[Middle English winewen from Old English windwian to fan or winnow, from wind1]