su·do·ku /suːˈdəʊkuː $ -ˈdoʊ-/ noun [countableC, uncountableU] a game in which you have to write numbers in a large square which is made up of 81 smaller squares. Each line of squares across and down, and each of the nine groups of nine squares, must contain the numbers 1 to 9 once only. 数独