The story
- Proto-Italic*wre-
- Latinre-
- Proto-Indo-European*spend-
- Proto-Indo-European*spondéyeti
- Proto-Italic*spondejō
- Proto-Italic*spondeō
- Latinspondeō
- Latinrespondeō
- Latinrespōnsum
- Old Frenchrespuns
- Middle Englishrespounse
- English todayresponse
From Middle English respounse, respons, from Old French respons, respuns, responce, ultimately from the Latin respōnsum, a nominal use of the neuter form of respōnsus, the perfect passive participle of respondeō, from re (“again”) + spondeō (“promise”). Doublet of responsum.
Etymology from Wiktionary, CC BY-SA 4.0.