1. (n.) 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.

2. (n.) Moral firmness; soundness; strength; validity; truth; certainty; -- as opposed to weakness or fallaciousness; as, the solidity of arguments or reasoning; the solidity of principles, truths, or opinions.

3. (n.) The solid contents of a body; volume; amount of enclosed space.

abidingness aplomb authenticity authoritativeness authority balance balanced personality body calculability callosity callousness changelessness closeness cogency combination compactness completeness comprehensiveness concreteness congestedness congestion consistence consistency constancy cool credit standing crowdedness denseness density dependability durability durableness duration durity endurance entireness entirety equilibrium exhaustiveness faithworthiness fastness firmness fixedness flintiness force frozenness fusion gluiness hardening hardness hardness of heart homeostasis identity immobility immobilization immovability immovableness immutability impenetrability impermeability imperturbability imporosity inclusiveness incompressibility individuality indivisibility induration inertia inextricability inflexibility intactness integrality integration integrity invariability invariableness inveteracy invincibility inviolability irreducibility irremovability jammedness justness lastingness long standing mass materiality nerve obduracy omnipresence oneness organic unity palpability particularity permanence permanency perpetualness persistence persistency pervasiveness ponderability predictability purity quiescence relative density reliability resistance restiveness rigidity rootedness sang-froid secureness security selfsameness simplicity singleness singularity solidarity solidification solidness solvency soundness specific gravity spissitude stability stable equilibrium stable state standing stasis staunchness steadfastness steadiness steady nerves steady state steeliness stoniness stoutness strength sturdiness substance substantiality substantialness tangibility temper thickness thoroughness torpor totality toughness trustworthiness ubiquity unchangeability unchangingness undeflectability undividedness unerringness unification uniformity unindebtedness uniqueness unity universality univocity unmovability unshakable nerves unshakableness unyieldingness validity vis inertiae viscidity viscosity viscousness weight wholeness