Synonyms for Solid as rock:

• adj.

  •constant (adjective)
  • uniform,
  • equable,
  • firm,
  • perpetual,
  • unalterable,
  • continual,
  • nonstop,
  • monotonous,
  • unchanging,
  • consistent,
  • together,
  • immutable,
  • unvarying,
  • even,
  • homogeneous,
  • uninterrupted,
  • unflappable,
  • permanent,
  • regular,
  • connected,
  • like the rock of gibralter,
  • invariable,
  • steady,
  • stable,
  • unbroken,
  • standardized.
  •secure (adjective)
  • bound,
  • adjusted,
  • strong,
  • sound,
  • fixed,
  • tenacious,
  • sure,
  • iron,
  • buttoned down,
  • solid,
  • immovable,
  • set,
  • tight,
  • Anchored,
  • locked,
  • staunch,
  • solid as a rock,
  • safe and sound,
  • Nailed,
  • fortified,
  • fast.
  •set (adjective)
  • ironclad,
  • well-set,
  • decisive,
  • definite,
  • prearranged,
  • Stipulated,
  • specified,
  • predetermined,
  • concluded,
  • rigid,
  • stiff-necked,
  • pat,
  • customary,
  • hanging tough,
  • rooted,
  • established,
  • scheduled,
  • intent,
  • locked in,
  • obstinate,
  • dead set on,
  • inveterate,
  • appointed,
  • pigheaded,
  • determined,
  • confirmed,
  • stubborn,
  • arranged,
  • agreed,
  • usual,
  • certain,
  • prescribed,
  • stated,
  • set in stone,
  • resolved,
  • settled,
  • entrenched,
  • resolute,
  • bent.
  •stable (adjective)
  • poised,
  • abiding,
  • perdurable,
  • durable,
  • substantial,
  • enduring,
  • secure,
  • lasting,
  • stout,
  • unchangeable,
  • stationary,
  • brick-wall,
  • deep-rooted,
  • reliable,
  • sturdy,
  • well-founded,
  • well-built,
  • tough,
  • stalwart,
  • balanced,
  • unwavering,
  • staying put,
  • calm,
  • safe.
  •steady (adjective)
  • changeless,
  • unfaltering,
  • unquestioning,
  • patterned,
  • never-failing,
  • steady-going,
  • unshaken,
  • unqualified.
  •well (adjective)
  • hardy,
  • able-bodied,
  • fine,
  • hale,
  • hearty,
  • chipper,
  • in good health,
  • flourishing,
  • bright-eyed,
  • alive and kicking,
  • wholesome,
  • wrapped tight,
  • up to par,
  • whole,
  • fresh,
  • trim,
  • sane,
  • right,
  • vigorous,
  • robust,
  • right as rain,
  • blooming,
  • strong as an ox,
  • great,
  • in the pink,
  • bushy-tailed,
  • fit,
  • husky.

• Other synonyms:

  •adj.
  • habitual,
  • stabile,
  • steadfast,
  • of a piece,
  • constant,
  • monochrome,
  • monophonic,
  • regularized,
  • unfluctuating,
  • non-stop.

Antonyms for Solid as rock:

• adj.

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