fraction

From Middle English fraccioun, meaning "a breaking," borrowed from Anglo-Norman and Old French fraccion, from Medieval Latin fractio, "a fragment or portion." That in turn traces to Latin fractio, "a breaking, a breaking into pieces," from fractus, the past participle of frangere, "to break."

The word began as an act of violence — a breaking — and settled into something calmer: a piece or portion, the mathematical sense we use today.

It's a doublet of the Italian frazione, both descending from the same Latin root, and it shares that root with English frangible, "easily broken."