1.
If you cast off something, you get rid of it because it is no longer necessary or useful to you, or because it is harmful to you. ( LITERARY )
The essay exhorts women to cast off their servitude to husbands and priests...
PHRASAL VERB : V P n (not pron)
2.
If you are on a boat and you cast off , you untie the rope that is keeping the boat in a fixed position.
He cast off, heading out to the bay.
PHRASAL VERB : V P