'ballista' originates from Latin, specifically the word 'ballista', which in turn comes from Greek 'βαλλιστής' (ballistēs), meaning 'missile-thrower', ultimately from the verb 'βάλλειν' (ballein) meaning 'to throw'.

'ballista' passed from Greek 'βαλλιστής' into Latin as 'ballista' in Classical and Late Latin and was adopted into Medieval Latin and Middle English as 'ballista', eventually becoming the modern English word 'ballista'.

Initially, it meant 'a missile-thrower' or 'engine for throwing missiles'; over time the term has remained close to that original sense but is now often used specifically for the torsion-powered bolt-throwing engine of ancient warfare.