Ghost

In folklore, a ghost is defined as the soul or spirit of a deceased person or non-human animal. Many people believe these spirits possess the ability to appear to the living.

Descriptions of these entities vary widely across different cultures and stories. Some accounts describe an invisible presence or a translucent, wispy shape. Other traditions depict ghosts as realistic, lifelike forms that resemble humans or animals.

These spirits are often thought to haunt specific locations, objects, or people associated with them during their lives.

There is a vast vocabulary used to describe different types of spirits. A poltergeist is a specific term, derived from a German word meaning "noisy ghost," used for spirits believed to move objects invisibly.

Other terms include apparition, phantom, specter, wraith, and shade. The word "spook" is a Dutch loanword that entered English via American English in the 19th century. A "revenant" refers to a deceased person returning from the dead to haunt the living, either as a disembodied spirit or an animated corpse. Some traditions also recognize a "fetch," which is the visible spirit of a person who is still alive.

Belief in the supernatural is considered a cultural universal. In many pre-literate folk religions, these ideas are categorized under animism or ancestor worship.

Some belief systems suggest a ghost never leaves Earth if no one remains to remember them. Many cultures distinguish between benign spirits involved in ancestor worship and malignant, restless ghosts. To manage these spirits, various religious and magical practices have developed. These include funeral rites, exorcisms, and spiritualism. Some traditions use ritual feeding to pacify the dead, such as during the Chinese Ghost Festival or Western All Souls' Day. Others use magical banishment to ensure spirits do not return to the material world.

Historically, the word "ghost" has undergone significant linguistic shifts. It originates from the Old English "gāst," meaning breath, spirit, or soul. This can be traced back to the Proto-Germanic "*gaistaz," which linguists reconstruct from a root meaning "fury" or "anger."

In the 9th century, the term was sometimes used to mean the "breath of God." It was not until the 14th century that the prevailing sense of a ghost as the visible soul of a dead person emerged. In ancient cultures, the soul was sometimes depicted as a bird or an animal. The Egyptian Book of the Dead shows deceased individuals appearing in the afterlife much as they did in life, including their specific clothing.

Modern science approaches the subject of ghosts with skepticism. The overwhelming consensus among scientists is that there is no proof that ghosts exist.

Because their existence cannot be proven false, ghost hunting is classified as pseudoscience. Despite this, a 2009 study by the Pew Research Center found that 18% of Americans claim to have seen a ghost. Scientists have investigated various biological and environmental reasons for ghost sightings. For example, older reports linked carbon monoxide poisoning to ghost-like hallucinations. Certain medications, such as zolpidem or diphenhydramine, may also cause rare hallucinations.

Recent medical research has explored connections between ghost sightings and neurological health. Some studies indicate that sightings may be related to degenerative brain diseases, such as Alzheimer's disease. Specifically, certain toxic and psychoactive plants contain anticholinergic compounds. These compounds are pharmacologically linked to neurodegeneration and conditions like dementia. Additionally, cases of progressive posterior cortical atrophy (PCA) have been noted to cause vivid hallucinations. This suggests that what people perceive as spirits may sometimes be explained by complex interactions within the human brain.

Beyond individual experiences, the concept of the spirit connects to broader philosophical and cultural systems. The idea of a soul as a "life force" or "breath" is found in many languages, such as the Latin "spiritus" and Greek "pneuma."

Anthropologists note that the idea of ghosts being composed of misty or airy material likely stems from observing human breath in cold climates. Whether viewed as a religious reality, a psychological phenomenon, or a cultural motif, the study of ghosts reveals how humans attempt to understand the transition between life and death.