means A V-shaped cut or indentation in an edge or surface, or a single step or grade up or down a scale.

from A linguistic accident: this word likely comes from misdividing the Old French phrase 'an oche' (a notch) into 'a notch' — the same slip that turned 'a napron' into 'an apron,' only running the opposite way. The French 'oche' meant a nick or groove cut into a tally stick, and probably traces back to a verb meaning 'to cut a notch.'