'antispastic' originates from the combining form 'anti-' (from Greek 'anti') meaning 'against' and 'spastic', ultimately from Greek 'spastikos' meaning 'drawing, convulsing'.

'spastikos' in Greek produced Late Latin/Medieval medical forms and the English adjective 'spastic'; the modern compound 'antispastic' was formed by prefixing 'anti-' to 'spastic' in medical usage.

Initially it denoted being 'against spasms' or 'opposing spasm'; in modern medical usage it specifically denotes an agent or effect that reduces spasticity.