testament (noun) – attestation, tribute, or proof; a will; a covenant
BREAKDOWN: TEST- (witness) + -MENT (act or state of)
— the Old and New Testaments are the two main parts of the Judeo-Christian Bible
This word is built on the root TEST-, which means witness.
Common TEST- words include contest, detest, and protest.
More esoteric TEST- words include intestacy and obtest.