A Copyediting reader recently asked me about the difference between testimony and testament. Although both terms relate to evidence, testimony specifically refers to evidence from a witness, while testament is “tangible proof or evidence,” according to American Heritage Dictionary. The terms share a common, if distant, root that reveals their relationship.
Testament entered English in 1290 from the Latin testāmentum, “a will,” which is from the Latin testārī, “to make a will,” according to the Chambers Dictionary of Etymology. Testārī, Chambers continues, comes from the Latin testis, “witness.” The idea is that the testament, the will, was a witness in a lawsuit to the deceased’s wishes.
Testimony entered English before 1382, referring to the Ten Commandments, as used in the Wycliffe Bible. It wasn’t until about 1425, says Chambers, that testimony picked up its legal meaning from a borrowing of the Old French testimonie and the Latin testimōnium, both meaning “evidence, proof.” Now, watch what happens when we pull apart testimony’s Latin ancestor.
Testimōnium, says Online Etymology, is from testis, “witness” and -monium, a suffix that means an “action, state, condition.” That testi- that is hiding in both in testament and testimony ultimately comes from the Proto-Indo-European (PIE) *tris- for “three,” as in the third party who gives witness.
From three to witness to evidence, it’s all relative.