'snake-legged' originates from Modern English, specifically the compound 'snake' + 'legged', where 'snake' referred to the reptile 'snake' and 'leg' meant 'limb'.

'snake' comes from Old English 'snaca' (from Proto-Germanic *snakaz); 'leg' comes from Old English 'leg' (from Proto-Germanic *lagjaz). The adjectival suffix '-ed' (forming 'legged') is from Old English adjectival/participle endings and later Modern English usage combined them into the compound adjective 'snake-legged'.

Initially it was a literal compound meaning 'having legs like a snake' and this literal sense has been retained; occasional figurative uses (e.g., describing sinuous movement) developed later.