The notoriously slippery term poetry usually refers to works written in verse — that is, with the sort of recurring rhythm called metre. Of course, that's far too simple a designation, as even the most basic consideration of free verse makes clear.

??? In some works of criticism, poetry and poem are used synecdochically for all literature. When the New Critics, for instance, talk about the interpretation of "the poem," their comments are meant to be understood to apply to all works of literature, even if lyric poetry was the form with which they were most comfortable.

From the Guide to Literary Terms by Jack Lynch.
Please send comments to Jack Lynch.
Note: This guide is still in the early stages of development.
Three question marks mean I have to write more on the subject. Bear with me.