'anti-vaxxer' originates from English, specifically a combination of the prefix 'anti-' (from Greek 'anti' meaning 'against') and 'vaxxer', where 'vax' is a colloquial shortening of 'vaccine' and the agent-forming suffix '-er' denotes 'a person who'.

'vaccine' itself traces to Latin 'vacca' meaning 'cow' (via Edward Jenner's use of cowpox), 'vax' emerged as an informal clipped form of 'vaccine' in late 20th century English, 'vaxxer' formed by adding '-er', and 'anti-' was prefixed in the late 20th/early 21st century to yield 'anti-vaxxer'.

Initially a descriptive label for people opposed to vaccination, 'anti-vaxxer' has taken on stronger social and often pejorative connotations, sometimes referring broadly to those resisting public-health vaccination efforts or believing vaccine-related misinformation.