'anesthesiant' originates from French, specifically the word 'anesthésiant', where 'anesthésier' meant 'to anesthetize' and the suffix '-ant' forms agent nouns.

'anesthésiant' was adopted into English as 'anesthesiant', and eventually became the modern English word 'anesthesiant'.

Initially, it meant 'a substance that induces anesthesia', and this meaning has remained the same in modern usage.