pathological

caused by or involving disease; compulsive or unhealthy

Roots

log / logy: word, speech, reasoning, study
path: feeling or suffering

Other words with the log / logy root

analogous: similar in a useful or structural way
analogy: comparison based on similarity
anthropology: the study of human beings
apologist: a defender of a person, idea, or cause
apology: expression of regret or defense
astrology: belief system mapping celestial positions to human affairs
biology: study of life
dialogue: conversation

Other words with the path root

antipathy: strong dislike
apathy: lack of feeling or concern
empathy: ability to understand another person's feelings
pathetic: arousing pity; weak or inadequate
sympathy: shared feeling or compassion

Pathological belongs to disease and suffering before it becomes a broader warning word.

The doctor separated ordinary fatigue from pathological sleepiness.

Pathological is strongest when the disease image stays visible. It can describe literal illness, or a pattern so unhealthy that it feels disease-like.