escheker

Old French escheker derived from Arabic shatranj (chess), which came from Sanskrit chaturanga. Escheker described a chessboard — the checked (squared) pattern. English adopted it as 'check' and 'checker'; the checked pattern became 'checkered.' The Exchequer — the British government's finance department — was named for the checkered cloth on which medieval accountants laid out their counters to calculate sums, using the board's squares as an abacus.

Checkers (draughts in British English) is played on the same board as chess — 8×8 squares — but with entirely different pieces and rules. Pieces move diagonally forward; captures are compulsory; pieces reaching the back row are crowned. The game's ancestor appears in Al-Qirq, an Arabic game played in 1000 CE; checkers proper (with the forced-capture rule) appears in French records from around 1100.

Checkers was among the first games mastered by computer AI. Marion Tinsley, the greatest checkers player in history, lost only seven games in his 45-year career; he was defeated by a computer program (Chinook, developed by Jonathan Schaeffer at the University of Alberta) twice in a 1994 match before he withdrew due to illness. Tinsley died months later. In 2007, Schaeffer's team proved that perfect checkers play results in a draw — checkers is 'solved.'

The checkered flag at the end of a motor race, the checkered pattern on police cars in the United Kingdom, 'a checkered past' (a mixed history of highs and lows): all derive from the escheker board. The game board became the pattern of consequence.