A cereal grass of genus Avena, especially Avena sativa.

• A widely cultivated plant grown in cool climates.

The edible seeds of the oat plant.

• Grain used for porridge, cereals, and animal feed.

A simple flute made from oat straw.

• Poetic or archaic usage.

A very small amount; a jot.

• Rare usage.

Initialism meaning of all time.

• Used after superlatives in rankings and lists.