Marianne Moore famously described the poet's job as creating 'imaginary gardens with real toads in them'. Now there's a definition! Except with horned frogs and a sweat-slingin', bow-legged prince or two.
We could say a poet artistically renders words in such a way as to evoke intense emotion or an aha! experience from the reader. We could say poets use economy of language and are miserly and unrelentingly critical in the way they apply words to a page. But let's not do this. Don't shackle poetry with definitions. It can't be done. Poetry has enormous power, ya'll. Poetry is imagination and will break those chains faster than a prairie fire with a tail wind. And like grasping at that wind, once you catch it...it's no longer wind.
--Jo VonBargen 2012