Synonyms for Solid as a rock:

• adj.

  •healthy (adjective)
  • well.
  •secure (adjective)
  • fixed,
  • immovable,
  • firm,
  • tenacious,
  • Anchored,
  • adjusted,
  • locked,
  • iron,
  • buttoned down,
  • fast,
  • Nailed,
  • fortified,
  • sound,
  • bound,
  • staunch.
  •set (adjective)
  • definite,
  • established,
  • arranged,
  • obstinate,
  • appointed,
  • stated,
  • hanging tough,
  • usual,
  • bent,
  • customary,
  • decisive,
  • scheduled,
  • regular,
  • pat,
  • certain,
  • predetermined,
  • settled,
  • determined,
  • concluded,
  • prescribed,
  • resolved,
  • ironclad,
  • specified,
  • steadfast,
  • intent,
  • unflappable,
  • confirmed,
  • resolute,
  • Stipulated,
  • pigheaded,
  • entrenched,
  • agreed,
  • rigid,
  • inveterate.
  •stable (adjective)
  • calm,
  • unalterable,
  • equable,
  • substantial,
  • balanced,
  • stationary,
  • abiding,
  • reliable,
  • well-founded,
  • stabile,
  • even,
  • uniform,
  • lasting,
  • permanent,
  • unwavering,
  • together,
  • safe,
  • unvarying,
  • brick wall,
  • enduring,
  • unchangeable,
  • immutable,
  • perdurable,
  • brick-wall,
  • deep-rooted,
  • staying put,
  • unfluctuating,
  • invariable,
  • stalwart,
  • poised.
  •steady (adjective)
  • patterned,
  • unfaltering,
  • unquestioning,
  • unqualified,
  • steady-going,
  • unshaken,
  • constant,
  • unchanging,
  • changeless.
  •well (adjective)
  • great,
  • in good health,
  • in the pink,
  • vigorous,
  • blooming,
  • husky,
  • alive and kicking,
  • wholesome,
  • hardy,
  • fine,
  • sane,
  • bushy-tailed,
  • hale,
  • hearty,
  • wrapped tight,
  • right,
  • strong as an ox,
  • fit,
  • flourishing,
  • fresh,
  • bright-eyed,
  • whole,
  • able-bodied,
  • strong as ox,
  • chipper,
  • right as rain,
  • up to par,
  • trim.

• Other synonyms:

  •
  • fireproof,
  • shockproof,
  • invulnerable,
  • heatproof,
  • ineradicable,
  • indestructible,
  • water-resistant,
  • inviolate,
  • irresistible,
  • sturdy,
  • unassailable,
  • heat-resistant,
  • unbreakable,
  • flameproof,
  • rustproof,
  • indissoluble,
  • shatterproof.
  •
  • durable,
  • unbeatable,
  • bombproof,
  • industrial-strength,
  • invincible,
  • incorruptible,
  • rooted,
  • bulletproof,
  • impregnable,
  • defensible,
  • well-built,
  • heavy-duty,
  • unshakable,
  • weatherproof.
  •
  • stout,
  • substantially,
  • Cast iron,
  • stubborn.
  •
  • robust,
  • waterproof.
  •
  • sure,
  • tough,
  • solid.
  •
  • tight.
  •
  • strong.

Antonyms for Solid as a rock:

• adj.

  • secure
    insecure, unfixed, uncertain, endangered, undecided, movable, unsafe, moving, unstable, changeable, unsure, loose, unfastened, flexible, Unsecure, impermanent, unprotected, unsteady, irresolute, weak, indefinite, broken, soft.
  • set
    unsettled, variable, wavering, infrequent, yielding.
  • stable
    imbalanced, unreliable, changing, vulnerable, temporary, shaky, undependable, different, intermittent, ephemeral, wobbly, inconstant, unsound, untrustworthy.
  • steady
    irregular, unfaithful, discontinuous.
  • well
    diseased, unsuited, poor, unlucky, infirm, inappropriate, unhealthy, little, rough, unfit, unfortunate, unsuitable, unhappy, ill, sick, incomplete, small.