'antipneumococcal' is formed from the combining prefix 'anti-' and the medical compound 'pneumococcal'. 'anti-' originates from Greek 'anti-' meaning 'against'. 'pneumo-' comes from Greek 'pneumōn' meaning 'lung', and 'coccal' derives from New Latin/Greek 'coccus' (from Greek 'kokkos') meaning 'berry' or 'seed', used for spherical bacteria.

'antipneumococcal' is a modern medical coinage (20th century onward) combining the prefix 'anti-' with 'pneumococcal' (itself from Neo-Latin/medical formation 'pneumococcus' for the bacterium). The element 'pneumococcus' came into English via scientific Latin/Greek usage and 'pneumococcal' was then paired with 'anti-' to denote agents acting against it.

Originally the components referred separately to 'against' and 'lung/berry-shaped bacterium'; over time they combined into a single technical adjective meaning 'acting against pneumococcus'.