'ballista' originates from Greek, specifically the word 'ballistēs' (βαλλιστής), where the root 'ballein' meant 'to throw'.

'ballistēs' (Greek) passed into Latin as 'ballista', was adopted into Medieval/Modern English as 'ballista', and the Latin plural form 'ballistae' is sometimes used in English texts.

Initially, it meant 'a machine for throwing missiles' and over time it has retained that basic meaning, now mainly used in historical or archaeological contexts.