completely (quitting, etc.); entirely; thoroughly; totally; wholly; resolutely; decisively; flatly; firmly; without hesitation
cleanly (cutting, snapping off, etc.); in a single blow
悪い習慣をすっぱり断つべきだ。
You should completely quit bad habits.
すっぱり諦めることにする。
I will decide to give up entirely.
タバコをすっぱり断った。
I quit smoking completely.