Webster's 1828 Dictionary
SOLIDNESS
n. 1. The quality of being firm, dense or compact; firmness; compactness; solidity; as of material bodies.
2. Soundness; strength; truth; validity; as of arguments, reasons, principles, etc.
Webster's 1913 Dictionary
SOLIDNESS
SOLIDNESS Sol "id *ness, n.
1. State or quality of being solid; firmness; compactness; solidity, as of material bodies.
2. Soundness; strength; truth; validity, as of arguments, reasons, principles, and the like.