Synonyms for Hard as nails:

• adj.

  •cutthroat (adjective)
  • ferocious,
  • pitiless,
  • merciless,
  • dog-eat-dog,
  • savage,
  • relentless,
  • bloodthirsty,
  • cruel,
  • vicious,
  • barbarous,
  • unprincipled.
  •determined (adjective)
  • strong-willed,
  • dogged,
  • pat,
  • set on,
  • persevering,
  • decisive,
  • buckled down,
  • serious,
  • intent,
  • on ice,
  • unfaltering,
  • unhesitating,
  • constant,
  • decided,
  • unflinching,
  • earnest,
  • purposeful,
  • resolved,
  • steadfast,
  • unwavering,
  • bent,
  • settled,
  • hard-as-nails,
  • mean business,
  • strong-minded,
  • bent on.
  •hard (adjective)
  • obdurate,
  • unpleasant,
  • hostile,
  • inclement,
  • stringent,
  • disagreeable,
  • unkind,
  • rugged,
  • antagonistic,
  • rancorous,
  • bleak,
  • harder,
  • unsparing,
  • brutal,
  • coldblooded,
  • grim,
  • cold,
  • intemperate,
  • stubborn,
  • unjust,
  • rigorous,
  • distressing,
  • dark,
  • unfeeling,
  • thick-skinned,
  • unrelenting,
  • grievous,
  • resentful,
  • stern,
  • austere,
  • strict,
  • dour,
  • cold-blooded,
  • intolerable,
  • perverse,
  • painful,
  • exacting,
  • unsympathetic,
  • cold fish,
  • angry,
  • severe,
  • vengeful,
  • callous,
  • harsh,
  • acrimonious,
  • bitter.
  •hard-bitten (adjective)
  • compressed,
  • rocky,
  • hardhanded,
  • adamantine,
  • iron,
  • indurate,
  • concentrated,
  • compact,
  • set,
  • Compacted,
  • consolidated,
  • hardbitten,
  • Indurated,
  • packed,
  • impenetrable.
  •hard-boiled (adjective)
  • rough,
  • inflexible,
  • obstinate,
  • headstrong,
  • hard-line,
  • hard-nosed,
  • firm.
  •hardened (adjective)
  • case-hardened,
  • prepared,
  • Habituated,
  • accustomed,
  • inured,
  • inaccessible,
  • contemptuous,
  • benumbed,
  • toughened,
  • unsubmissive,
  • disdainful,
  • Unrepenting,
  • unashamed,
  • irreverent,
  • impious.
  •puissant (adjective)
  • powerful,
  • potent.
  •strong (adjective)
  • durable,
  • able-bodied,
  • energetic,
  • solid,
  • hearty,
  • heavy-duty,
  • capable,
  • robust,
  • forcible,
  • substantial,
  • stout,
  • reinforced,
  • enduring,
  • unyielding,
  • well-built,
  • staunch,
  • well-founded,
  • sound,
  • stark,
  • tenacious,
  • heavy,
  • sturdy,
  • active,
  • well-made,
  • fixed,
  • steady,
  • forceful,
  • hale,
  • vigorous,
  • muscular,
  • in fine feather,
  • athletic,
  • mighty,
  • stable,
  • stalwart,
  • big,
  • strapping,
  • hardy,
  • secure,
  • sinewy,
  • able.
  •tough (adjective)
  • cohesive,
  • indigestible,
  • Withstanding,
  • dense,
  • tight,
  • resilient,
  • leathery,
  • unbreakable,
  • molded,
  • rigid,
  • resistant,
  • stiff,
  • lusty,
  • fibrous,
  • healthy,
  • conditioned,
  • brawny,
  • flinty,
  • seasoned,
  • fit,
  • Steeled.
  •unbending (adjective)
  • Incompliant,
  • dug in,
  • single-minded,
  • uptight,
  • resolute,
  • uncompromising,
  • reserved,
  • hold one's ground,
  • formal,
  • standing one's ground,
  • distant,
  • intractable,
  • hold the line,
  • Unswayable,
  • crisp,
  • inelastic,
  • inexorable,
  • standing pat.

• n.

  •durability (noun)
  • grit,
  • heart,
  • permanence,
  • constancy,
  • lastingness,
  • Durableness,
  • endurance,
  • backbone,
  • moxie,
  • imperishability,
  • persistence,
  • stamina,
  • imperishabilities,
  • intestinal fortitude,
  • gutsiness,
  • starch,
  • guts,
  • staying power,
  • stick-to-itiveness.

• Other synonyms:

  •
  • Hard-handed,
  • hard-bitten.

Antonyms for Hard as nails:

• adj.

  • cutthroat
    kind, gentle.
  • determined
    wavering, undetermined, hesitating, vacillating, undecided, changeable.
  • hard
    malleable, easy, pliant, bright, flexible, nice, facile, cheerful, doubtful, sunny, simple, pliable, questionable, pleasant, sensitive, uncertain, inexact, soft, mild, sympathetic, disputable, yielding, untrue, merciful.
  • heartless
    giving, feeling, friendly, considerate, warmhearted, compassionate, caring.
  • imperturbable
    irritable, jittery, Perturbable, touchy, excitable.
  • insensitive
    sensate, mindful, responsive, impressionable, touched, concerned, aware.
  • strong
    complacent, unimportant, undependable, slack, unfixed, loose, insignificant, unstable, delicate, ineffective, inactive, moderate, Mistakable, weak, easy-going, Unpowerful, intermittent, sluggish, agreeable, pale, untrustworthy, unable, fragile, infirm, obscure, little, uncaring, indistinct, impotent, feeble, indefinite, idle, broken, lethargic, vague, laid-back, unhealthy, lazy, small, vulnerable, wobbly, inept, irresolute, low, moving.
  • tough
    tender, controllable.
  • unbending
    relaxed, bending.

• n.

  • durability
    weakness, poorness, fear, unreliability, impermanency, cowardice.