Oxford Advanced American Dictionary

Definition of tic-tac-toe noun from the Oxford Advanced Learner's Dictionary

tic-tac-toe

noun (also tick-tack-toe)
tic-tac-toe pronunciation English ˌtɪk tæk ˈtəʊ tic-tac-toe pronunciation American ˈtoʊ
(North American English) (British English noughts and crosses) [uncountable]
 
a simple game in which two players take turns to write Os or Xs in a set of nine squares. The first player to complete a row of three Os or three Xs is the winner.