Phrasal verbs, also called two-word verbs, are idiomatic expressions wherein the second element of the verb (the adverb or particle) is not necessarily predictable.
finish someone or something off Fig.
to complete some activity being performed on someone or something.
Let's finish this one off and go home.
A verb combined with an adverb or a preposition, or sometimes both, to give a new meaning.
A compilation of 50 phrasal verbs.