grievous

1. causing fear or anxiety by threatening great harmExamples: "a dangerous operation"; "a grave situation"; "a grave illness"Synonyms: dangerous, grave, grievous, life-threatening, serious, severe

2. causing or marked by grief or anguishExamples: "a grievous loss"; "a grievous cry"; "her sigh was heartbreaking"Synonyms: grievous, heartbreaking, heartrending

3. of great gravity or crucial import; requiring serious thoughtExamples: "grave responsibilities"; "faced a grave decision in a time of crisis"; "a grievous fault"Synonyms: grave, grievous, heavy, weighty

4. shockingly brutal or cruelExamples: "murder is an atrocious crime"; "a grievous offense against morality"; "a grievous crime"Synonyms: atrocious, flagitious, grievous, monstrous