In traditional belief, a ghost is the soul or spirit of a deceased person or animal that can appear, in visible form or other manifestation, to the living. Descriptions of the apparition of ghosts vary widely: The mode of manifestation can range from an invisible presence to translucent or wispy shapes, to realistic, life-like visions. The deliberate attempt to contact the spirit of a deceased person is known as necromancy, or in spiritism as a séance.
The belief in manifestations of the spirits of the dead is widespread, dating back to animism or ancestor worship in pre-literate cultures. Certain religious practices—funeral rites, exorcisms, and some practices of spiritualism and ritual magic—are specifically designed to appease the spirits of the dead. Ghosts are generally described as solitary essences that haunt particular locations, objects, or people they were associated with in life, though stories of the phantom armies, ghost trains, phantom ships, and even ghost animals and numbers have also been recounted.
The English word ghost continues Old English gást, from a hypothetical Common Germanic *gaistaz. It is common to West Germanic, but lacking in North and East Germanic (the equivalent word in Gothic is ahma, Old Norse has andi m., önd f.). The pre-Germanic form was *ghoisdo-s, apparently from a root denoting "fury, anger" reflected in Old Norse geisa "to rage." The Germanic word is recorded as masculine only, but likely continues a neuter s-stem. The original meaning of the Germanic word would thus have been an animating principle of the mind, in particular capable of excitation and fury (compare óðr). In Germanic paganism, "Germanic Mercury," and the later Odin, was at the same time the conductor of the dead and the "lord of fury" leading the Wild Hunt.
Besides denoting the human spirit or soul, both of the living and the deceased, the Old English word is used as a synonym of Latin spiritus also in the meaning of "breath, blast" from the earliest (9th century) attestations. It could also denote any good or evil spirit, i.e. angels and demons; the Anglo-Saxon gospel refers to the demonic possession of Matthew 12:43 as se unclæna gast. Also from the Old English period, the word could denote the spirit of God, viz. the "Holy Ghost." The now prevailing sense of "the soul of a deceased person, spoken of as appearing in a visible form" only emerges in Middle English (14th century). The modern noun does, however, retain a wider field of application, extending on one hand to soul, spirit," vital principle, mind or psyche, the seat of feeling, thought and moral judgement; on the other hand used figuratively of any shadowy outline, fuzzy or unsubstantial image, in optics, photography and cinematography especially a flare, secondary image or spurious signal.
The synonym spook is a Dutch loanword, akin to Low German spôk (of uncertain etymology); it entered the English language via the United States in the 19th century. Alternative words in modern usage include spectre (from Latin spectrum), the Scottish wraith (of obscure origin), phantom (via French ultimately from Greek phantasma, compare fantasy) and apparition. The term shade in classical mythology translates Greek σκιά, or Latin umbra, in reference to the notion of spirits in the Greek underworld. "Haint" is a synonym for ghost used in regional English of the southern United States, and the "haint tale" is a common feature of southern oral and literary tradition. The term poltergeist is a German word, literally a "noisy ghost," for a spirit said to manifest itself by invisibly moving and influencing objects.
Wraith is a Scottish dialectal word for "ghost, spectre, apparition." It came to be used in Scottish Romanticist literature, and acquired the more general or figurative sense of "portent,omen." In 18th- to 19th-century Scottish literature, it was also applied to aquatic spirits. The word has no commonly accepted etymology; OED notes "of obscure origin" only. An association with the verb writhe was the etymology favored by J. R. R. Tolkien. Tolkien's use of the word in the naming of the creatures known as the Ringwraiths has influenced later usage in fantasy literature. Bogie is an Ulster Scots term for a ghost, and appears in Scottish poet John Mayne's Hallowe'en in 1780.
A revenant is a deceased person returning from the dead to haunt the living, either as a disembodied ghost or alternatively as an animated ("undead") corpse. Also related is the concept of a fetch, the visible ghost or spirit of a person yet alive.