The Collaborative International Dictionary
Laticlave \Lat"i*clave\, n. [L. laticlavus, laticlavium; latus broad + clavus nail, a purple stripe on the tunica: cf. F. laticlave.] (Rom. Antiq.) A broad stripe of purple on the fore part of the tunic, worn by senators in ancient Rome as an emblem of office.
Wiktionary
n. (context historical English) A badge of two wide purple stripes, worn by senators and certain other high-ranking people in ancient Rome.
Wikipedia
In Ancient Roman regalia, a laticlave, or clavus, was a broad stripe or band of purple on the fore part of the tunic, worn by senators as an emblem of office, from which the difference of the tunica angusticlavia, and laticlavia.
This ornament, according to some, was called clavus ("nail") as being set with little round plates of gold, or silver, like the heads of nails.
Cantelius maintained that the clavus consisted of a kind of purple flowers, sewn upon the cloth.