[f. Gr. τριώνυμ-ος having three names, f. τρι-, TRI- + ὄνομα name.] A name consisting of three terms; a trinomial name in botany or zoology; TRINOMIAL B. 2. So Trionymal a. = TRINOMIAL A. 2, TRINOMINAL.
1656. Blount, Glossogr., Trionimal..., that hath three names.
[1691. Tomlinson, in Ray, N. C. Words, s.v. Brock, The animal is trionymus, badger, brock, or gray.]
1884. Coues, in Auk, Oct., 321. Tronym, an onym consisting of three terms.
1884. J. A. Allen, ibid., 352. Even a trinomial (or trionymal) system fails to meet the requirements of the case.