unforgiving
1. [ adjective ] harsh and severe
Synonyms: uncharitable
Examples:

"I hope I'm not being uncharitable but he really is a bore" "unjust and uncharitable criticism"

Related terms: ungenerous
2. [ adjective ] not to be placated or appeased or moved by entreaty
Synonyms: grim stern relentless inexorable unrelenting unappeasable
Examples:

"grim determination" "grim necessity" "Russia's final hour, it seemed, approached with inexorable certainty" "relentless persecution" "the stern demands of parenthood

Related terms: implacable
3. [ adjective ] unwilling or unable to forgive or show mercy
Examples:

"a surly unforgiving old woman"

Related terms: forgiving revengeful
Similar spelling:   unforgivingly
  unforgivably
  unforgivable
  unforbearing
  unafraid
  unforgettably
  unforgettable