Tertiary

1. (a.) Being of the third formation, order, or rank; third; as, a tertiary use of a word.
2. (a.) 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. (a.) Later than, or subsequent to, the Secondary.
4. (a.) Growing on the innermost joint of a bird's wing; tertial; -- said of quills.
5. (n.) 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.
6. (n.) The era, period, or formation.
7. (n.) One of the quill feathers which are borne upon the basal joint of the wing of a bird. See Illust. of Bird.