'respondent' originates from Latin, specifically the word 'respondere' (present participle 'respondens'), where 're-' meant 'back' and 'spondere' meant 'to pledge' or 'to promise'.

'respondent' changed from the Medieval Latin word 'respondens' and Old French 'respondant' and eventually became the modern English word 'respondent' through Middle English.

Initially, it meant 'answering' (the present participle sense of 'respondere'), but over time it evolved into the noun meaning 'one who answers'.