1. To separate grain from its husks, or chaff: Sam winnowed the granular material by tossing it up in the air or blowing air and letting the wind blow the unwanted parts away.
2. To examine something in order to remove the bad, unusable, or undesirable parts; The workers winnowed the fruit in order to eliminate the decaying ones from the edible fruit
3. To examine closely in order to separate the good from the bad; to sift: The chairman winnowed the topics of discussion first before the conference began.
4. To remove (people or things that are less important, desirable, etc.) from a larger group or list: The least qualified applicants were winnowed out of the initial pool.
5. To make (a list of possible choices) smaller by removing the less desirable choices: The number of candidates has been winnowed, that means that it has been narrowed down or whittled down to seven.

This sense of winnow is often followed by "down": He needs to winnow down his options.

6. Etymology: Old English windwian, from wind, "air in motion, paring down". Cognate with Old Norse vinza, Old High German winton, "to fan, to winnow"; "to throw (grain) apart"; from Latin vannus, "winnowing fan".

The same concept describes Latin ventilare, "winnow", the source of ventilate in English which came from ventus, "wind".