a V-shaped indentation

a slit or cut in a surface used as a record

any of the holes in a belt for receiving the tongue of the buckle

a degree or point on a scale

a step or level

NAmer a deep narrow pass; a gap

to make a notch in (something)

(often + up) to mark or record (e.g. an addition to a score) with or as if with a notch

(+ up) to score or achieve (e.g. a success)