Tic-tac-toe side is a term used to describe the three rows of three squares that make up the game of tic-tac-toe. The two crossword solutions for this term are EXES and XES. EXES is a 4-letter word meaning two people who were formerly in a romantic relationship, while XES is a 3-letter word meaning the plural form of the letter X. Both words can be used to refer to the sides of a tic-tac-toe board.