One of the three basic states of matter. A solid forms from either a liquid or a gas (the other two states of matter) because, as the energy of the atoms decreases, they coalesce in the relatively ordered, three-dimensional structure of a solid. All solids have the ability to support loads applied either perpendicular (normal) or parallel (shear) to a surface. Solids can be crystalline (as in metals), amorphous (as in glass), or quasicrystalline (as in certain metal alloys), depending on the degree of order in the arrangement of the atoms.

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