binomial vs binominal

binomial is a noun but binominal is not a noun.

Word	Noun	Adjective	Verb	Adverb
binomial	Yes	Yes	No	No
binominal	No	Yes	No	No

As adjectives, binomial and binominal are synonyms defined as:

binomial and binominal: having or characterized by two names, especially those of genus and species in taxonomies

binomial (noun)	binominal (noun)
(mathematics) a quantity expressed as a sum or difference of two terms; a polynomial with two terms

binomial (adjective)	binominal (adjective)
of or relating to or consisting of two terms	having or characterized by two names, especially those of genus and species in taxonomies
having or characterized by two names, especially those of genus and species in taxonomies