The word "nomial" can be confusing to spell because it is not a commonly used term. However, its spelling is simple once broken down phonetically. Its pronounced as "noh-mee-uh l" with the stress on the second syllable. The first syllable is pronounced as "no" with an "oh" sound. The second syllable is pronounced as "mee" with a long "ee" sound. The third syllable is pronounced as "uh" with a schwa sound. Overall, the word is an easier one to spell if one writes it out phonetically.
A single name or term in algebra.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.