Phrasal verbs consists of a basic verb + another word or words. The two or three words that make up a phrasal verb form a short 'phrase' - which is why we call them 'phrasal verbs'.
sleep something off
to sleep while the effects of liquor or drugs pass away.
Bill is at home sleeping off the effects of the drug they gave him.
Phrasal verbs are compound verbs that result from combining a verb with an adverb or a preposition. The resulting compound verb is idiomatic.
A compilation of 50 phrasal verbs.