rhymeless
/ˈraɪmleɪs/Definitions
1. adjective
Lacking rhyme or poetic meter; unable to be rhymed with
“The poet struggled to find a rhyme for the complex word, making her poem rhymeless.”
2. noun
A word or phrase that cannot be rhymed with another word
“The dictionary listed several rhymeless words, making it challenging for the poet to write a rhyming poem.”