Merriam-Webster Collegiate Dictionary - prose

 I. noun  Etymology: Middle English, from Anglo-French, from Latin prosa, from feminine of prorsus, prosus, straightforward, being in ~, contraction of proversus, past participle of provertere to turn forward, from pro- forward + vertere to turn — more at pro-, worth  Date: 14th century  1.  a. the ordinary language people use in speaking or writing  b. a literary medium distinguished from poetry especially by its greater irregularity and variety of rhythm and its closer correspondence to the patterns of everyday speech  2. a prosaic style, quality, or condition  II. adjective  Date: 14th century  1. of, relating to, or written in ~  2. prosaic  III. intransitive verb  (~d; prosing)  Date: 1642  1. to write ~  2. to write or speak in a prosaic manner