'antimissionary' originates from English formation using the prefix 'anti-' (from Greek 'antí' meaning 'against') + 'missionary' (from Latin 'missionarius', from 'missio' meaning 'a sending').

'antimissionary' was formed in modern English by combining 'anti-' and 'missionary'; 'missionary' itself comes via Old French and Late Latin from Latin 'missio' (sending) and 'missionarius' (one sent).

Initially it simply meant 'against missions' or 'opposed to missionaries'; this basic meaning has been retained, applied to people, groups, writings, or attitudes hostile to missionary activity.