Cucumber comes through earlier English from Anglo-French cucumbre. Behind it is Latin cucumis, whose stem is cucumer-.
Cucumis and cucumer- are a noun and its stem, not two languages or successive borrowings. The source also records Middle English, compressed in these three cards.
Sources
- Merriam-Webster: cucumber
Word History gives Anglo-French cucumbre and the Latin noun/stem pair cucumis, cucumer-, through Middle English.
- Anglo-Norman Dictionary · cucumbre
Meanings of the older forms on the word path.
- Online Etymology Dictionary · cucumber
Meanings of the older forms on the word path.
- logeion.uchicago.edu · cucumis
Meanings of the older forms on the word path.