The story
- Latinred-
- Proto-Indo-European*h₁em-
- Proto-Indo-European*h₁émeti
- Proto-Italic*emō
- Latinemō
- Latinredimō
- Old Frenchredimer
- Middle Englishredemen
- English todayredeem
From Middle English redemen, modified from Old French redimer, from Latin redimō (“release; obviate; atone for”), itself from red- (“back; again”) + emō (“buy; gain, take, procure”).
Etymology from Wiktionary, CC BY-SA 4.0.