What does "testament" mean?

Testament: One of the two distinct revelations of God's purposes toward man; a covenant; also, one of the two general divisions of the canonical books of the sacred Scriptures, in which the covenants are respectively revealed; as, the Old Testament; the New Testament; -- often limited, in colloquial language, to the latter. He is the mediator of the new testament . . . for the redemption of the transgressions that were under the first testament. Heb. ix.