One who or that which checks or verifies something.

One who makes a check mark.

The clerk who tallies cost of purchases and accepts payment.

One who hinders or stops something.

A playing piece in the game of checkers (British: draughts).

A pattern of alternating colours as on a chessboard.

An individual square appearing in such a pattern.

The fruit of the wild service tree or chequer tree, Photinia villosa, syn. Sorbus terminalis

(transitive) To mark in a pattern of alternating light and dark positions, like a checkerboard.

(intransitive) To develop markings in a pattern of alternating light and dark positions, like a checkerboard.