Solidity

Noun

 * 1) The state or quality of being solid.
 * 2) Moral firmness; validity; truth; certainty.
 * 3)  The solid contents of a body; volume; amount of inclosed space.

Adjectives for Solidity
combined; moral; little; primitive; costly; imposing; mellow; false; stable.

Thesaurus
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

Etymology
From soliditas:

Translations

 * Romanian:

Synonyms

 * compactness
 * consistency
 * density
 * fullness
 * hardness
 * massiveness
 * solidness
 * soundness
 * strength

Antonyms

 * fluidity
 * hollowness
 * instability
 * openness
 * weakness