'balistarius' originates from Medieval Latin, specifically the word 'balistarius', where 'balista' meant 'a missile-throwing engine' and the suffix '-arius' meant 'pertaining to or connected with'.

'balistarius' changed from Latin 'ballista' (ultimately from Greek 'balliste' < Greek root 'ballein' meaning 'to throw') and entered Medieval Latin as 'balistarius', later appearing in some Medieval and early modern historical texts as a learned or technical term.

Initially, it meant 'operator of a ballista' and the core meaning has largely remained the same, though the term is now archaic and mainly used in historical descriptions.