The Collaborative International Dictionary
Tertiary \Ter"ti*a*ry\, n.; pl. Tertiaries.
(R. C. Ch.) 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.(Geol.) The Tertiary era, period, or formation.
(Zo["o]l.) One of the quill feathers which are borne upon the basal joint of the wing of a bird. See Illust. of Bird.
Wiktionary
n. (plural of tertiary English)
Wikipedia
Usage examples of "tertiaries".
Each of the secondary rings at the corners fed four tertiaries in sequence via a diverter arrangement like the one they had seen in the fan-shaped vault.
Further wraparound in the tertiaries gave another current-multiplication factor of ten, producing six hundred amperes in each.
That wide belt of stuff just inside the big ring must be where the tertiaries are buried.
A bit of highly significant information that had come via a wildly circuitous routing: Rhomandi men placed in every capped node throughout the Web, including the secondaries and tertiaries could send messages almost as fast as the Towers when they had to.
Maur itum had the same number of satellites, but the number of functional, capped tertiaries in Rhomatum far outstripped the island web.
Even the unsettled tertiaries had lights erected along them, though the lights barely glim mered, and the land itself had long since been claimed on speculation toward the time when even those minuscule intersections would be capped and lowered.
And monstrous though these Tertiaries were, who can fail to find a grandeur in their doomed upward striving?