Adjective grievous has 4 senses
- dangerous, grave, grievous, serious, severe, life-threatening - 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"
Antonyms: noncritical, noncrucial (indirect, via critical)
- grievous, heartbreaking, heartrending - causing or marked by grief or anguish; "a grievous loss"; "a grievous cry"; "her sigh was heartbreaking"; "the heartrending words of Rabin's granddaughter"
Antonym: joyful (indirect, via sorrowful)
- grave, grievous, heavy, weighty - 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"
Antonym: unimportant (indirect, via important)
- atrocious, flagitious, grievous, heinous, monstrous - shockingly brutal or cruel; "murder is an atrocious crime"; "a grievous offense against morality"; "a grievous crime"; "no excess was too monstrous for them to commit"
Antonym: good (indirect, via evil)
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