\Tri*no"mi*al\, a. (Nat. Hist.)
Consisting of, or involving the use of, three terms; as, a
trinomial systematic name specifying the genus, species, and
variety.

\Tri*no"mi*al\, n. [Pref. tri- + -nomial as in
binomial: cf. F. trin[^o]me.] (Math.)
A quantity consisting of three terms, connected by the sign +
or -; as, x + y + z, or ax + 2b - c^{2}.

\Tri*no"mi*al\, a. (Math.)
Consisting of three terms; of or pertaining to trinomials;
as, a trinomial root.