'hairlessness' is a Modern English formation from the noun 'hair' plus the suffixes '-less' and '-ness' (where '-less' meant 'without' and '-ness' formed nouns meaning 'state or quality'). The element 'hair' originates from Old English 'hær', ultimately from Proto-Germanic '*hairą' meaning 'hair'.

'hair' changed from Old English 'hær' to Middle English 'hair'; the adjective-forming suffix '-less' comes from Old English 'lēas' and the noun-forming '-ness' from Old English 'nes(s)e'. The compound 'hairless' appeared in earlier Modern English, and adding '-ness' produced 'hairlessness'.

Initially the elements conveyed 'hair' + 'without' + 'state' (i.e. 'the state of being without hair'), and this basic meaning has been preserved into modern usage.