Crowd-sourced! I asked my friends on Facebook, “Tell me a thing you think a poem is, and a thing you think a poem is not.” Here are some of the answers I got:

• A poem is original, not a cliche.
  — Kirsten Huscusson
• I think a poem is words and a poem is not words.
  — Emily Doolittle
  
  
• Have you read Mary Ruefle? Madness Rack & Honey is one long essay I want to excerpt in answer to your query. I read the book that it is in daily.

  Poetry is often the only way to discover and become and describe that which we so desperately need to have in our world, between the lines of what is or we are – it lives in the spaces between and we carve it into existence with sound and pixels and ink.

  Poems are both birth and death. — Lisa Rokusek

• Poetry is vulnerability. Poetry is not packaged neatly for the masses.
  — Jamie Herron
• A poem is a distillation of a thought, a memory, or a feeling, but it is not a confession
  — Sheree Renée Thomas
• Poetry is where knowing quickens into music.
  — Klyd Watkins
• a poem is emotional truth/a poem is not factual
  — Julene T. Weaver
• every
  Thing
  is a Poem

  Not what a poem is Not
  rather
  what it need not be

  it need not be prettymoonjuneballoonflutteringlashessunsethandinhandandhearts

  but it can

  it can be
  the sound of choking
  in a hidden prison
  the numbness
  of three jobs two kids no words

  mass graves
  wildflowers
  a roach cleaning her antennae

  it can be
  the devout cliches
  of a dying elder

  the droning angst
  of a teenager
  trying
  to kill a secret

  bad grammar
  bad form

  yet with a voice
  a DNA
  of need

  a sloppy scrawl
  of run-on prose

  rhyme slanted
  hard enough to snap
  stuttered meter
  of a diseased heart

  It can be garbage
  repurposed
  or left to decay
  slipping the bonds
  of language

  the mnemonic
  of atoms whose existence
  writes itself
  — Elissa Malcohn