i-adjective
more than one can eat; cannot finish eating
Used when the amount of food is too large to finish. Often appears in negative potential form.
この料理は多すぎて、一人では食べきれない。
This dish is too much for one person to finish.
食べきれない分は冷凍しておきましょう。
Let's freeze the portion we can't finish.
The base verb meaning 'to eat up completely'; 食べ切れない is its negative potential form.
Compound of 食べ (stem of 食べる 'to eat') + 切れない (negative potential of 切る 'to cut', here meaning 'to do completely').