In a Binomial setting, there are only two possible outcomes per try. Depending on what you want, you call one of the possibilities Fail and the other one Succes.
You may call rolling a 6 with a die Succes, and a non-6 a Fail. Depending on the conditions of the game, rolling a 6 may cost you money, and you may want to reverse the terms.
There are only two possible outcomes per try, and you may name them as you want: White-Black, Heads-Tails, whatever.
Usually the one you use as #P# in calculations is called (probability of) Succes.