Morbid means unhealthily fascinated by death and dark things. A morbid interest, morbid curiosity, do not be morbid.
Morbid curiosity is the standard phrase for wanting to look at something unpleasant, and it is very nearly universal. In medicine, morbid is a neutral technical word meaning relating to disease — morbid anatomy, morbidly obese — and morbidity means the rate of illness in a population, as against mortality, the rate of death. Note that those two words are constantly swapped in reporting and mean quite different things.
1adjectivemorbidUnhealthily fascinated by death and dark things.
“He has a morbid interest in old murder cases.”
2adjectiverelatingRelating to disease.
“Morbidity is the rate of illness and mortality the rate of death.”
morbid is a quality of dwelling on death or disease.
Latin morbidus means diseased, from morbus, a disease. The medical sense is the original; the sense of dwelling on death is an English development and about two hundred years old.
Proto-Indo-European
*mer-
Latin
morbidus
English, today
morbid
Built from
From Latin morbidus. From Latin morbidus (“diseased”), from morbus (“sickness”), itself from the root of morī (“to die”) or directly from Proto-Indo-European mer- (“to rub, pound, wear away”).
Etymology from Wiktionary, CC BY-SA
Practised in Sharper Adjectives