'antigenic' originates from modern English formation combining 'antigen' with the suffix '-ic', where 'antigen' comes from early 20th-century German 'Antigen' (coined as an abbreviation of 'antibody generator'); 'anti-' meant 'against' and the root 'gen' (from Greek) meant 'to produce'.

'antigen' was coined in early immunology (from a contraction of 'antibody generator' in German/English scientific usage) and, by adding the adjective-forming suffix '-ic' (from Greek -ikos via Latin -icus), the modern adjective 'antigenic' entered scientific English in the 20th century.

Initially it referred specifically to a substance that generates antibodies; over time it has come to mean more generally 'relating to antigens or their properties', including the ability to provoke immune responses or to react with antibodies.