'unequal-awned' originates as an English compound of 'unequal' and 'awn'. 'unequal' ultimately comes from Latin, specifically from 'in-' + 'aequālis', where 'in-' meant 'not' and 'aequālis' meant 'equal'; 'awn' originates from Old English (early Germanic) words for a bristle or beard-like projection.

'unequal' passed into Middle English via Old French/Anglo-Norman forms (e.g. 'unequal, inegal') from Latin 'aequālis', while 'awn' was used in Old English to denote a bristle on grasses; the compound 'unequal-awned' is a Modern English botanical formation used to describe plants with awns of differing lengths.

Initially the parts meant 'not equal' (unequal) and 'bristle/awn' (awn); together in botanical usage they have retained a literal combined meaning: 'having awns of unequal length.'