determination; decision; resolve
Often used in the phrase 踏ん切りがつく (to make up one's mind) or 踏ん切りをつける (to resolve to do something). Implies overcoming hesitation.
I can't seem to make up my mind and am hesitating about changing jobs.
彼はついに踏ん切りをつけて、留学することにした。
He finally made up his mind and decided to study abroad.