Event with equally likely possible outcomes (4-2)
(Other definitions for toss-up that I've seen before include "Use of a coin to choose" , "Fifty-fifty chance" , "It helps you pick" , "Flip of a coin" .)
(Other definitions for tossup that I've seen before include "The throwing of a coin to decide outcome" , "A gamble - flip a coin" , "An even chance, like flip of coin" , "Even chance or risk" , "Flip in the air - it's a gamble" .)