checker

Etymology 1

check + -er

noun

1. One who or that which checks or verifies something.
   So, keep in mind that Microsoft Word’s Spelling tool is as much a “typo” tool as a checker of spelling. 1992, Neil J. Salkind, Applying Macintosh: Solutions, Ideas, and Tools, Macmillan Publishing Company, page 205
2. One who makes a check mark.
   "Essentially," said a senior vice president of the FHLBB of Dallas, "we were checkers of boxes." 1989, M. Manfred Fabritius, William Borges, Saving the Savings and Loan
3. The clerk who tallies cost of purchases and accepts payment.
   There was a long line at the grocery store because the checker was so slow.
4. One who hinders or stops something.

Etymology 2

From Middle English cheker, aphetic from Anglo-Norman escheker (“chessboard”), from Latin scaccarium, thus ultimately morpheme-for-morpheme cognate to etymology 1.

noun

1. A playing piece in the game of checkers (British: draughts).
2. A pattern of alternating colours as on a chessboard.
3. An individual square appearing in such a pattern.

verb

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

Etymology 3

Alteration of chequer.

noun

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