Synonyms of the word

adamantine

• adj. Made of adamant, or having the qualities of adamant; incapable of being broken, dissolved, or penetrated.
• adj. Like the diamond in hardness or luster.

adamant

• adj. Firm; unshakeable; unyielding; determined.
• adj. (of an object) Similar to the adamant; very difficult to break, pierce, or cut.
• n. An imaginary rock or mineral of impenetrable hardness; a name given to the diamond and other substances…
• n. An embodiment of impregnable hardness.
• n. A magnet; a lodestone.

carbon

• n. (uncountable) The chemical element (symbol C) with an atomic number of 6.
• n. (countable) An atom of this element, in reference to a molecule containing it.
• n. (countable, informal) A sheet of carbon paper.
• n. (countable, informal) A carbon copy.
• n. A fossil fuel that is made of impure carbon such as coal or charcoal.
• n. (ecology, uncountable) Carbon dioxide, in the context of global warming and climate change.
• n. A carbon rod or pencil used in an arc lamp.
• n. A plate or piece of carbon used as one of the elements of a voltaic battery.

hard

• adj. (of material or fluid) Having a severe property; presenting difficulty.
• adj. (personal or social) Having a severe property; presenting difficulty.
• adj. Unquestionable.
• adj. (of a road intersection) Having a comparatively larger or a ninety-degree angle.
• adj. (slang, vulgar, of a male) Sexually aroused.
• adj. (bodybuilding) Having muscles that are tightened as a result of intense, regular exercise.
• adj. (phonetics, not comparable).
• adj. (art) Having a severe property; presenting a barrier to enjoyment.
• adj. (not comparable) In the form of a hard copy.
• adv. (manner) With much force or effort.
• adv. (manner) With difficulty.
• adv. (obsolete) So as to raise difficulties.
• adv. (manner) Compactly.
• adv. (now archaic) Near, close.
• n. (countable, nautical) A firm or paved beach or slope convenient for hauling vessels out of the water.
• n. (uncountable, drugs, colloquial, slang) crack cocaine.

inexorable

• adj. Unable to be persuaded; relentless; unrelenting.
• adj. Impossible to stop or prevent; inevitable.
• adj. Adamant; severe.

inflexible

• adj. Not flexible; not capable of bending or being bent; stiff; rigid; firm; unyielding.
• adj. Not willing to change, e.g. one's opinion or habits; obstinate; stubborn; resolute; determined.

intransigent

• adj. Unwilling to compromise or moderate a position; unreasonable; irreconcilable; stubborn.
• n. A person who is intransigent.