1. Causing great physical or mental pain.
Thesaurus: agonizing, intense, painful, unbearable, intolerable, extreme, severe, acute, sharp, insufferable, searing, torturous.
2. colloq Extremely bad or irritating.
Etymology: 16c: from Latin excruciare to torture, from cruciare, cruciatum to crucify.
As in "The pain of a gall bladder attack can be excruciating".