grievous

If something is called grievous, you better take it seriously. Grievous is used to describe horrible things like tragedies or crimes. If you have a grievous wound, a band aid simply won't do.

Grievous is derived from the noun grief, which means "sadness." When something is grievous, therefore, it's not just bad, but so bad that it causes unusually intense shock or sadness. It's often used to describe crimes and other bad deeds that go beyond mere criminality and into the world of cruelty. For example, it's harmful to steal from someone; it's grievous to steal from them and then, having stolen their stuff, beat them up or kill them.

Definitions of grievous
1

adj causing or marked by grief or anguish

“a grievous loss”
“a grievous cry”
Synonyms:
heartbreaking, heartrending
sorrowful
experiencing or marked by or expressing sorrow especially that associated with irreparable loss

adj causing fear or anxiety by threatening great harm

grievous bodily harm”
Synonyms:
dangerous, grave, life-threatening, serious, severe
critical
being in or verging on a state of crisis or emergency

adj shockingly brutal or cruel

“a grievous offense against morality”
“a grievous crime”
Synonyms:
atrocious, flagitious, monstrous
evil
morally bad or wrong

adj of great gravity or crucial import; requiring serious thought

“a grievous fault”
Synonyms:
grave, heavy, weighty
important, of import
of great significance or value