The term X X X can be filled in with four letter words CHIS, TENS, six letter word KISSES, seven letter word HUNDRED and fifteen letter word TICTACTOEENDING. CHIS stands for Chief Information Security Officer, a job title that is responsible for the security of an organization's information systems. TENS stands for Transcutaneous Electrical Nerve Stimulation, a type of therapy used to relieve pain. KISSES stands for Keep It Simple, Stupid, a phrase used to remind people to keep their ideas simple and straightforward. HUNDRED stands for Hundredth, which is the ordinal form of the number 100. Finally, TICTACTOEENDING stands for Triple Tic-Tac-Toe Ending, which is a game ending in which all nine squares on the tic-tac-toe board are filled with either an X or an O.