The origin of the word tribrach is the Greek τρίβραχυς, derived from the prefix τρι- "three" and the adjective βραχύς "short".
The earliest mention of the word τρίβραχυς in a Greek writer recorded in Liddell and Scott's lexicon is in the grammarian Hephaestion (2nd century AD), who lists the tribrach among the possible forms which a trochaic foot could take.
[7] In Latin poetry a tribrach is never found in the works of Virgil, Ovid, or Catullus, since the hexameter and hendecasyllable metres do not allow a series of more than two syllables.
It is, however, fairly common in iambic and trochaic verse as used in Roman comedy in writers such as Plautus and Terence.
In iambic and trochaic metres a tribrach can replace either an iamb (u –) or a trochee (– u) at any place except immediately before the end of the line or before the central dieresis.