A tripalium (or Trepalium, from "tripaliare", latin, to constrain probably from Latin "trēs", "tria" three + "pālus" stake) has at least three significations related to a labor in a constraining context. The structure and original use of the tripalium is far from clear; many attempts to explain it appear to be based on nothing more than the word's literal meaning of "three stakes".
Following, this word is a more or less disputed root of modern work related words in the Mediterranean area, like Travail (French, but this origin is still very disputed because Tripalium as designing Work, leading to travail, appeared only in the XIIIth century ), Trabajo (Spanish), travaglio (Italian), trabalho (Portuguese), traballo (Galician) and treball (Catalan) or Travel (English).
However, Tripalium clearly described a structure made of wood designed to immobilise a big and mostly reticent or fiery animal (horse, oxen, cow) in order to allow a secure and comfortable examination or care since the Roman Empire. It is the clear and undisputed origin of the french technical word "travail" describing the same structure, and still used in France today in a farrier context.
Further, a tripalium described any structure of wood beams of a framework of wood, also "Trabicula", and per extension a beam as part of it in the Middle Ages. These Trabicula are the direct source of an architectural particularity proper to the city of Lyon, the Traboules, transverse structures to access more apartments. With the evolution of the french language, Tripalium could have became "traveil", "traval", "traveaul".
Third, Tripalium described since the Roman Empire an instrument involving three stakes or poles ("palus", latin), used to punish only slaves. The subject would be tied to the tripalium and tortured e.g. burnt with fire.
The two oldest well known references to Tripalium meaning Torture were found in Cicero's In Verrem ("Against Verres"), in 70 BC and 582 AD, in an earlier Council of Auxerre forbidding clerics to assist to torture sessions. Indeed, the historical records concerning torture in the ancient Roman empire provide far more information about famous cases where it was applied, or the legalities thereof, than about the means of torture and references to impalement.