The Collaborative International Dictionary of English v.0.48:
Rhymester \Rhyme"ster\, n. A rhymer; a maker of poor poetry. --Bp. Hall. Byron. [1913 Webster]WordNet (r) 3.0 (2006):
rhymester n 1: a writer who composes rhymes; a maker of poor verses (usually used as terms of contempt for minor or inferior poets) [syn: rhymer, rhymester, versifier, poetizer, poetiser]