'barkless' originates from Old English elements: the noun 'bark' (from Old English 'beorc' meaning 'birch' or the bark of a tree) combined with the suffix '-less' (from Old English 'lēas' meaning 'without' or 'free from').

'bark' continued from Old English into Middle English as 'bark' referring to tree covering; the adjective-forming suffix '-less' attached in Middle English to produce compounds such as 'barkless', which evolved into the modern English 'barkless'.

Initially used literally to mean 'without bark' (of trees); over time it has also been used to describe animals that do not bark, keeping the general sense 'lacking bark' or 'without barking'.