A phrasal verb is a verb plus a preposition or an adverb which creates a different meaning from the original verb. These include things like 'figure out', 'close down', 'screw up', 'come across', 'spell out', 'keep up with', and 'stick up'. Among many others.
Some grammarians think that only idiomatic conjunctions should count as verbal phrases. (For example, you could not deduce the meaning of 'nod off' from the words 'nod' and 'off'; therefor it is idiomatic.) They would call literal conjunctions (for example 'break in') verb-particle constructions. Others think that even literal compound verbs should be considered phrasal verbs.
Many phrasal verbs are separable; for example the idiomatic form of 'break in' (to break in a new pair of shoes) can be split 'break x in' (to break the shoes in). This is still a single phrasal verb, despite being smeared across the sentence. Others phrasal verbs, such as 'count on' and 'look down on' cannot be split.
A phrasal verb may also be called a verb-particle construction, verb phrase, multi-word verb, compound verb, or two-part verb (or sometimes a three-part verb, as in 'come up with' or 'live up to').
This WU has been on my scratchpad for five years. New Year's resolution: clear off some scratchpads.