Tertiary

Part of speech: noun (n.)

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. Addis & Arnold.

2. The Tertiary era, period, or formation.

3. One of the quill feathers which are borne upon the basal joint of the wing of a bird. See Illust. of Bird.

Part of speech: adjective (a.)

1. Being of the third formation, order, or rank; third; as, a tertiary use of a word. Trench.

2. 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. (CH3)3C.OH.

3. Later than, or subsequent to, the Secondary.

4. Growing on the innermost joint of a bird's wing; tertial; -- said of quills. Tertiary age. (Geol.) See under Age, 8. -- Tertiary color, a color produced by the mixture of two secondaries. "The so-called tertiary colors are citrine, russet, and olive." Fairholt. -- Tertiary period. (Geol.) (a) The first period of the age of mammals, or of the Cenozoic era. (b) The rock formation of that period; -- called also Tertiary formation. See the Chart of Geology. -- Tertiary syphilis (Med.), the third and last stage of syphilis, in which it invades the bones and internal organs.