'awn' originates from Old English (or Middle English usage of the same root), specifically the word 'æfn/æfn' (recorded forms vary), where the root referred to a beard or hair-like growth on plants.

'awn' appeared in Middle English in forms such as 'awn(e)' referring to a beard or bristle on grain; it developed from earlier Old English/West Germanic forms and remained associated with hair- or bristle-like plant structures into modern English.

Initially it referred to a beard or long hair (on people or figuratively on grain), and over time the meaning narrowed to the specific modern sense of a bristle-like projection on grasses and seeds.