For all the people who have up to now been forced to suffer by ending up on my KJV-Onlyism-bashing post when all they want (according to my blog stats and referring links) is “a definition of adament,” here is the OED’s definition:
adamant, n. and a.
Name of an alleged rock or mineral, as to which vague, contradictory, and fabulous notions long prevailed. The properties ascribed to it show a confusion of ideas between the diamond (or other hard gems) and the loadstone or magnet, though by writers affecting better information, it was distinguished from one or other, or from both. The confusion with the loadstone ceased with the 17th c., and the word was then often used by scientific writers as a synonym of diamond. In modern use it is only a poetical or rhetorical name for the embodiment of surpassing hardness; that which is impregnable to any application of force.
1. a. Without identification with any other substance.
† 2. a. Identified with the diamond. Obs.
† b. as the natural opposite of the loadstone. Obs.
† 3. a. Identified with the loadstone or magnet. Obs.
† b. as the natural opposite of the diamond. Obs.
† c. fig. A magnet, centre of attraction. Obs.
† 4. Confusing 3 with 1 or 2. Obs.
B. adj. Unshakeable, inflexible, esp. to be adamant, stubbornly to refuse compliance with requests. (The point at which the n. use passed into adj. is not determinable.)
Hence adamantly adv.
Also note that it is spelled adamant, not adament.