The Collaborative International Dictionary
Rhythmer
Rhythmer \Rhyth"mer\ (r[i^]th"m[~e]r or r[i^][th]"-), n. One who writes in rhythm, esp. in poetic rhythm or meter.
One now scarce counted a rhythmer, formerly admitted
for a poet.
--Fuller.
Wiktionary
rhythmer
n. One who writes in rhythm, especially in poetic rhythm or meter.