'antiauxin' originates from Modern scientific English, specifically formed by the prefix 'anti-' (from Greek 'anti-' via Latin) meaning 'against' and the element 'auxin' from New Latin 'auxin', ultimately from Greek 'auxein' meaning 'to increase' or 'to grow'.

'antiauxin' is a modern coinage from 20th-century botanical and physiological literature created by combining 'anti-' and 'auxin'; it did not evolve from a medieval English form but from the scientific formation process in New Latin/modern English.

Initially it denoted simply 'against auxin'; over time it has been used specifically to mean 'a chemical that antagonizes or inhibits auxin action' in plant physiology, a meaning that has remained stable within the scientific context.