Lewis Short
trĭgōn (noun M) : τρίγων or τρίγωνον
* A kind of ball for playing with, esp. in the baths, Mart. 4, 19, 5; 7, 72, 9; 12, 83, 3: fugio campum lusumque trigonem,a game of ball,Hor. S. 1, 6, 126.
Charlton T. Lewis, Charles Short, A Latin Dictionary