Word Origin & History
testamentlate 13c., "last will disposing of property," from L. testamentum "a will, publication of a will," from testari "make a will, be witness to," from testis "witness," from PIE *tris- "three," on the notion of "third person, disinterested witness." Use in reference to the two divisions of the Bible (c.1300)
is from L.L. vetus testamentum and novum testamentum, loan-translations of Gk. palaia diatheke and kaine diatheke. L.L. testamentum in this case was a mistranslation of Gk. diatheke, which meant both "covenant, dispensation" and "will, testament," and was used in the former sense in the account of the Last Supper (see
testimony) but subsequently was interpreted as Christ's "last will."