inexorable

adjective3

1. •
   Impossible to prevent or stop; inevitable.

   • […] but inexorable yron detaines him in the dungeon of the night, fo that (pure creature) hee can neither traffique with the mercers and tailers as he was wont, nor dominere in tavernes as hee ought. — 1592
2. •
   Unable to be persuaded; relentless; unrelenting.
3. •
   Adamant; severe.