'sheath' originates from Old English, specifically the word 'sceath' (also written 'scēath'), where it meant 'covering' or 'scabbard'.

'sheath' changed from Old English 'sceath' through Middle English forms such as 'scheth'/'sheth' and eventually became the modern English word 'sheath'.

Initially, it meant 'a covering or case (typically for a blade)', and this basic meaning has largely remained the same in modern usage.