morbid
Focused on death or suffering in an unhealthy, gloomy way.
Morbid describes a focus on unpleasant subjects like death, disease, or decay that feels unhealthy, excessive, or obsessive. If your friend can't stop talking about gruesome details from a scary movie days after watching it, or spends all their time reading about disasters and tragedies, you might say they're being morbid.
The word suggests dwelling on dark subjects in a way that feels gloomy or obsessive, going beyond normal curiosity about difficult topics. Everyone wonders about serious things sometimes, and that's natural. But morbid means returning to these subjects repeatedly in a brooding way. A student writing a thoughtful report about a historical tragedy is being serious and respectful. A student who keeps bringing up frightening details just to disturb classmates is being morbid.
In medicine, doctors use morbid more technically to describe diseases or unhealthy conditions. Morbidity refers to the presence of illness in a population. But in everyday conversation, calling something morbid usually means it's focused on death or suffering in an uncomfortable, brooding way that most people would rather avoid.