*solidity*

n. [ L. soliditas: cf. F. solidité. ] 1. The state or quality of being solid; density; consistency, -- opposed to fluidity; compactness; fullness of matter, -- opposed to openness or hollowness; strength; soundness, -- opposed to weakness or instability; the primary quality or affection of matter by which its particles exclude or resist all others; hardness; massiveness. [ 1913 Webster ]

That which hinders the approach of two bodies when they are moving one toward another, I call solidity. Locke. [ 1913 Webster ]

2. Moral firmness; soundness; strength; validity; truth; certainty; -- as opposed to weakness or fallaciousness; as, the solidity of arguments or reasoning; the solidity of principles, triuths, or opinions. [ 1913 Webster ]

3. (Geom.) The solid contents of a body; volume; amount of inclosed space. [ 1913 Webster ]

Syn. -- Firmness; solidness; hardness; density; compactness; strength; soundness; validity; certainty. [ 1913 Webster ]