'anhydrate' originates from scientific English, formed from the privative prefix 'an-' (from Greek 'an-' meaning 'without') plus 'hydrate' (ultimately from Greek 'hydōr' meaning 'water').

'Hydrate' entered English via French 'hydrate' (from Greek 'hydōr' “water”); the prefix 'an-' (from Greek) was added in 19th‑century chemical nomenclature to create the modern English term 'anhydrate'.

Initially, it meant a substance or state “without water,” and in technical use it still denotes the water-free form or the act of removing water.