Definition of grievous

• causing fear or anxiety by threatening great harm; "a dangerous operation"; "a grave situation"; "a grave illness"; "grievous bodily harm"; "a serious wound"; "a serious turn of events"; "a severe case of pneumonia"; "a life-threatening disease"
• causing or marked by grief or anguish; "a grievous loss"; "a grievous cry"; "her sigh was heartbreaking"; "the heartrending words of Rabins granddaughter"
• of great gravity or crucial import; requiring serious thought; "grave responsibilities"; "faced a grave decision in a time of crisis"; "a grievous fault"; "heavy matters of state"; "the weighty matters to be discussed at the peace conference"