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 - ticktacktoe [N. Amer], ticktacktoo [N. Amer], tick-tack-toe [N. Amer], tic-tac-toe [N. Amer], noughts and crosses [Brit]