'anti-jammer' originates from Modern English, formed by the prefix 'anti-' (from Greek 'anti' meaning 'against') and the agent noun 'jammer' (from English 'jam' + suffix '-er', meaning 'one that jams').

'jam' as a verb meaning 'to block or squeeze' appears in Early Modern English (with uncertain earlier origins), 'jammer' arose as an agent noun (one that jams) in the 20th century with radio and signal-interference technology, and 'anti-jammer' developed in late 20th century Modern English as electronic countermeasure technology matured.

Initially, 'anti-' meant 'against' and 'jam' meant 'to block or interfere'; combined in modern usage the term evolved to mean 'a device or system that opposes or defeats a jammer.'