late 14c., from Old English windwian "to fan, winnow," from wind "air in motion, paring down," see wind (n.1). Cognate with Old Norse vinza, Old High German winton "to fan, winnow," Gothic diswinþjan "to throw (grain) apart."
She stood there winnowing grain all day in the field
The wind was winnowing her hair
the wind winnowed the grass
winnow the finalists from the long list of applicants
the winnowing was done by women