Meaning of trinomial

tri•no•mi•al

Pronunciation: (trī-nō'mē-ul), [key]
— adj.
  1. consisting of or pertaining to three terms.
    1. pertaining to a scientific name comprising three terms, as of genus, species, and subspecies or variety.
    2. characterized by the use of such names.
—n.
  1. an expression that is a sum or difference of three terms, as 3x + 2y + z or 3x + 2x + x.
  2. a trinomial name, as Rosa gallica pumila.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.