A phrase, consisting of a verb and either or both of a preposition or adverb, that has idiomatic meaning.
A two-word verb, consisting of a verb and a "small" adverb or particle, that has an idiomatic meaning not easily predictable from the individual parts.
An idiomatic expression in general.
An established expression whose wording is subject to little or no variation, and which may or may not be idiomatic.