'crossbowman' originates from English as a compound of 'crossbow' + 'man', where 'crossbow' referred to the weapon and 'man' meant a person or soldier.

'crossbow' itself was formed in Middle English (e.g. 'crosse-bowe' or 'crousbowe'), from elements meaning 'cross' (from Latin 'crux' via Old French/Old Norse influence) + 'bow' (Old English 'boga'); the agentive compound 'crossbowman' arose in later Middle English to denote a user of the weapon.

Initially it meant 'a man who operated or used a crossbow' and this basic sense has largely remained the same in modern usage.