Synonyms of the word

inexorable

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

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.

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.

grim

• adj. dismal and gloomy, cold and forbidding.
• adj. rigid and unrelenting.
• adj. ghastly or sinister.
• adj. (Britain, slang) disgusting; gross.

implacable

• adj. Not able to be placated or appeased.
• adj. Adamant; immovable.

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.

relentless

• adj. Unrelenting or unyielding in severity.
• adj. Unremitting, steady and persistent.

stern

• adj. Having a hardness and severity of nature or manner.
• adj. Grim and forbidding in appearance.
• n. (nautical) The rear part or after end of a ship or vessel.
• n. (figuratively) The post of management or direction.
• n. The hinder part of anything.
• n. The tail of an animal; now used only of the tail of a dog.
• n. A bird, the black tern.

unappeasable

• adj. not able to be appeased or satisfied.

unforgiving

• adj. Unwilling or unable to forgive or show mercy.
• adj. Having no allowance for weakness.

unrelenting

• adj. Not relenting; having no pity; not being or becoming lenient, mild, gentle, or merciful; unyielding; inflexibly…