The usual sense, of course, is “threefold,” and in this sense the word is fully equivalent to triple.
Whereas treble came to us from the Old French, of the same spelling and meaning, which, in turn, was derived from the Popular Latin tripulus, triple came directly from the latter source.
The original Latin form was triplex, from the Greek triplous, “threefold.”
The musical sense of treble seems to be from the soprano part having been the third part to be added to harmonized musical composition, in about the fifteenth century.
