solidness (Noun) — 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.
solidness (Noun) — The consistency of a solid.
solidness (Noun) — The quality of being substantial or having substance.
solidness (Noun) — The quality of being solid and reliable financially, factually or morally. ex. "the solidness of her faith gave her enduring hope"