A phrase that combines a verb with a preposition or adverb or both and that functions as a verb whose meaning is different from the combined meanings of the individual words.
Phrasal Verb:
drain away [for something]
Meaning:
to flow away.
Example:
All the water drained away and exposed the mud and rocks on the bottom of the pond.
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.