The word "morbid" entered the English language in the 1650s. It derives from the Latin adjective morbidus ("diseased" or "sickly"), which stems from the Latin noun morbus meaning sickness, disease, or ailment.  Because disease and decay were traditionally associated with physical weakness and the approach of death, the word was initially used in purely medical and anatomical contexts.  By the 1830s, the meaning expanded into the psychological and emotional realm.  It came to describe an unhealthy, unwholesome, or excessive focus on things like death, decay, and tragedy.  

According to the Oxford English Dictionary, the adjective "morbid" was first used in English in 1656.  It was recorded in the writings of the English philosopher and theologian Henry More, where it appeared in the medical and pathological sense of "pertaining to disease".  By the 1830s, the definition shifted from physical disease to unwholesome or excessive mental states—such as an unhealthy fixation on death, decay, or tragedy. 

The concept of the "morbid"—which centers on death, violence, and the macabre—is a vital storytelling tool. It satisfies morbid curiosity, an evolutionary mechanism allowing audiences to explore fears and model potential threats in a safe, fictional environment. 

Why the Morbid is Essential in Storytelling: Incorporating the dark and macabre into a narrative serves several key purposes:  
Building Psychological Resilience: Engaging with frightening or dystopian worlds allows audiences to subconsciously practice effective coping strategies. It helps process anxieties regarding the unknown.  
Deepening Empathy: Confronting suffering and tragic themes allows viewers or readers to explore profound existential questions and the shared human experience of grief.  
Testing Moral Boundaries: Morbid elements—such as monstrous villains or life-and-death dilemmas—force characters to make difficult choices. This reveals their true values and drives dramatic tension.  
Fostering an Appreciation of Life: By exploring decay and mortality, stories often remind audiences of the preciousness and randomness of life, generating a stark contrast between darkness and light.