Poetry- an Indefinable Definition
Poetry can rhyme, or be rhythmic. It can be descriptive, or nonsensical. It can have meter, stanzas, quatrains, or any number of stylistic qualities or formats. It can be critiqued- have essays written about it, like this one. It has symbolism, metaphors, and alliteration. It's meaning can be argued. It's merits can be objectively studied.
None of that matters. Poetry, really, is just about one thing. Trying to put into words just what you feel inside about a certain thing. It is by no means perfect or accurate, and it couldn't possibly describe exactly what you feel, but when that perfect poem is written, the poem that makes you feel a little gasp somewhere in the back of your heart, when a poem written five hundred years ago still means something to someone today, that is poetry. It is the imperfect attempt to capture what it means to be alive.