Tulane University defines an ore as a body of material from which one or more valuable substances can be extracted. For example, bauxite ore is mined and refined to extract aluminum.
root sheath the epidermic layer of a hair follicle. sheath of Schwann neurilemma. synovial sheath synovial membrane lining the cavity of a bone through which a tendon moves. tendon sheath a lubricated fibrous or synovial layer of tissue in which the tendon is housed and through which it moves.
A sheath knife is a fixed-bladed knife that fits in a sheath of leather or other material such as nylon or kevlar. The sheath is used to protect the knife and as a carrier. The blades vary in size, shape and construction. In Australian law, sheath knife has a different definition. In this case, they are a type of non-folding, fixed-blade knife which has a sheath which withdraws into its handle, thus giving something of the effect of an out-the-front flick knife.