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
lash someone or something down
to tie someone or something down.
The villain lashed Nell down to the railroad tracks.
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.