n. A prose poem; a work written in prose but incorporating poetic imagery and rhythms.
2013
At a reading last night, one writer called her prose-poems "proems."
2011
He read a variety of forms of poetry, including librettos, verse meant to be set to music; sestinas, poems structured with six stanzas of six lines and a final triplet; sonnets; villanelles, nineteen-line poems with two rhymes throughout; and, surprisingly, prose poems — what Fort called "proems."
1994 (earliest)
This in turn leads on…to the idea of the pebble which Brathwaite skimmed over the surface of the sea as a boy on Brown's Beach and which ultimately became an important trope in his poetry…The idea is pursued in a proem (i.e., a prose poem, a genre Brathwaite employs a good deal in his most recent work) which explores the idea that sand is the pebble ground down to its nam or spiritual essence.
There's a much older sense of the word proem that refers to a preface, preamble, or similar work that serves to introduce a piece of writing. That sense has been in the language for about 600 years since its first appearance in The Canterbury Tales (spelled proheme).