A game in which two players alternately put crosses and circles in one of the compartments of a square grid of nine spaces; the object is to get a row of three crosses or three circles before the opponent does WordNet 3.0 & Open English WordNet

Tic-tac-toe, noughts and crosses, or Xs and Os is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid with X or O. The player who succeeds in placing three of their marks in a horizontal, vertical, or diagonal row is the winner. Wikipedia

Paper-and-pencil game for two players Wikidata

A two-player game played on a three-by-three grid, in which players take it in turns to place their respective symbol (either a nought or a cross) in a cell of the grid, the objective being to form a row, column or diagonal of three of one's own symbol. Wiktionary

A game in which two players take turns putting circles and crosses on a 3x3 grid and try to get three of the same symbols in a line. Wiktionary

Game. Wiktionary (translation)