Solidness

State or quality of being solid; firmness; compactness; solidity, as of material bodies.

Soundness; strength; truth; validity, as of arguments, reasons, principles, and the like.

the quality of being solid and reliable financially or factually or morally; "the solidity of the evidence worked in his favor"; "the solidness of her faith gave her enduring hope"

the state in which a substance has no tendency to flow under moderate stress; resists forces (such as compression) that tend to deform it; and retains a definite size and shape

the quality of being substantial or having substance