From the Merriam-Webster Dictionary:

Dedicaton

Main Entry: ded�i�ca�tion
Pronunciation: "de-di-'kA-sh&n
Function: noun
Date: 14th century
1 : an act or rite of dedicating to a divine being or to a sacred use
2 : a devoting or setting aside for a particular purpose
3 : a name and often a message prefixed to a literary, musical, or artistic production in tribute to a person or cause
4 : self-sacrificing devotion
- ded�i�ca�to�ry /'de-di-k&-"tOr-E, -"tor-/ adjective

As in, You have to practice if you want to be a successful band. You have to have dedication. That's means you can't call :30 minutes before practice and cancel it because someone else called and wants you to watch movies that their house. That means you have to give a little but of fun up, even if it means telling someone you have plans at the time they want you to come over, but you'd be happy to reschedule another time to watch movies.