'toxoid' originates from English, specifically formed from the word 'toxin' (ultimately from Greek 'toxikon', where 'toxon' meant 'bow' and 'toxikon' came to mean 'poison for arrows') and the suffix '-oid' (from Greek '-oeidēs') meaning 'resembling' or 'like'.

'toxoid' was coined in English in the early 20th century to name detoxified bacterial toxins used in vaccines; 'toxin' itself entered English via Modern Latin 'toxicum' from Greek 'toxikon', and the combining form '-oid' has been used in English to form adjectives/nouns meaning 'like' or 'resembling'.

Initially, roots related to 'toxin' referred to poisonous substances; over time 'toxoid' came to denote a nonpoisonous, immunogenic form of a toxin used for vaccination rather than a harmful poison.