the.com/testament

means A testament is something whose continued existence serves as proof or evidence of a quality, achievement, or belief — and in its older, legal sense, a will declaring what's to be done with your estate after death.

from From Latin testamentum, 'a will,' built from testari, 'to bear witness,' which itself traces back to testis, 'witness.' The link between 'witnessing' and 'last will' is direct: a will is literally a document in which you testify, before witnesses, to your final wishes. The word's spread into English owes much to the Bible — the Old and New Testaments are so named because they're understood as the old and new 'covenants' or solemn attestations between God and humanity. From there, 'testament' loosened into general use for anything that stands as living proof of something else.