'lymphoid-reactive' originates from New Latin/Late Latin and Latin/Greek: 'lymphoid' comes from New Latin 'lymphoides' where the element 'lymph-' (from Latin 'lympha', from Greek 'lymphe') meant 'clear fluid' and the suffix '-oid' (from Greek '-oeidēs') meant 'like'; 'reactive' comes from Latin prefix 're-' + Latin verb 'agere' (via Late Latin/Old French forms leading to English 'react'), where 're-' meant 'again' and 'agere' meant 'to do or drive'.

'lymph' entered English from Latin 'lympha' (via Late Latin/Old French) and was used in medical contexts; the suffix '-oid' was attached in medical Latin/English to form 'lymphoid' in the 19th century. 'React' and then the adjective-forming '-ive' produced 'reactive' (from Late Latin/French sources). The compound 'lymphoid-reactive' arose in 20th-century medical English to describe lymphoid tissue showing reactive changes rather than neoplastic change.

Initially, 'lymphoid' meant 'like lymph' and 'reactive' meant 'capable of reacting'; over time, as a compound used in pathology and clinical medicine it evolved to mean specifically 'lymphoid tissue showing a reactive (non-neoplastic) response or change'.