'lymph-reactive' originates from English, formed by combining 'lymph' (from Latin 'lympha', ultimately from Greek 'lymphe', where 'lymphe' referred to clear water or bodily fluid) and 'reactive' (from Latin components 're-' meaning 'again' and a root related to 'agere' meaning 'to do' via the verb 'react').

'lymph' entered English via Medieval Latin 'lympha' and Old French/Medieval English adaptations; 'reactive' derives from Latin 'reactivus' (built from 're-' + 'act-' from Latin 'agere'/'actus'), passed into French as 'réactif' and then into modern English as 'reactive'; the compound formation 'lymph-reactive' is a modern English medical/technical compound combining the two elements.

Initially, the components meant 'relating to lymph (fluid/tissue)' and 'capable of reacting or producing a response'; over time the compound came to mean specifically 'producing or showing a reactive response in lymphatic tissue or lymph nodes' in medical contexts.