1. Being of the third formation, order, or rank; third; as, a tertiary use of a word.
2. (Science: chemistry) Possessing some quality in the third degree; having been subjected to the substitution of three atoms or radicals; as, a tertiary alcohol, amine, or salt. Cf. Primary, and secondary.
3. (Science: geology) Later than, or subsequent to, the secondary.
4. (Science: zoology) Growing on the innermost joint of a bird's wing; tertial; said of quills. Tertiary age.
(Science: medicine) The third and last stage of syphilis, in which it invades the bones and internal organs.
Origin: L. Tertiarius containing a third part, fr. Tertius third: cf. F. Tertiaire. See Tierce.
1. A member of the third order in any monastic system; as, the franciscan tertiaries; the Dominican tertiaries; the Carmelite tertiaries. See Third Order, under Third.
2. (Science: geology) The Tertiary era, period, or formation.
3. (Science: zoology) One of the quill feathers which are borne upon the basal joint of the wing of a bird.