The Collaborative International Dictionary
Rhymeless \Rhyme"less\, a.
Destitute of rhyme.
--Bp. Hall.
Wiktionary
a. (context linguistics English) Not rhymable, having no perfect rhymes.
WordNet
Usage examples of "rhymeless".
Whereas hitherto I had never stopped searching for a word that would rhyme with you, Tulla, that tank backing into position and those screaming glasses showed your Cousin Harry the way to a rhymeless language: from then on I wrote simple sentences, and now that a certain Herr Brauxel has advised me to write a novel, I am writing a normal rhymeless novel.
Harry sends rhymeless picture postcards and fails to find the headquarters of the Air Force division that had been promised him.
His cries of discovery ran like a tuneless, rhymeless trailsong through what would have been a silent journey were it left to Tyorl to provide conversation.
Wonder piled on wonder as the crusaders parade with their blood-bright banners to the rumble-roar of the drums, rhythmless as thunder, rhymeless as pulse.
As I finished typing this I realized the idiot machine might lock itself into perpetual motion, grinding out rhymeless, meterless verse forever unless I worked out a way to cancel that command.
He makes many experiments, one of the strangest being the introduction of rhymeless lines at regular intervals.