The paranormal can best be thought of as a subset of pseudoscience. What sets the paranormal apart from other pseudosciences is a reliance on explanations for alleged phenomena that are well outside the bounds of established science. Thus, paranormal phenomena include extrasensory perception (ESP), telekinesis, ghosts, poltergeists, life after death, reincarnation, faith healing, human auras, and so forth. The explanations for these allied phenomena are phrased in vague terms of "psychic forces", "human energy fields", and so on. This is in contrast to many pseudoscientific explanations for other nonparanormal phenomena, which, although very bad science, are still couched in acceptable scientific terms. The English word ghost continues Old English gást, from a hypothetical Common Germanic *gaistaz. It is common to West Germanic, but lacking in North Germanic 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" or "blast" from the earliest attestations (9th century). It could also denote any good or evil spirit, such as 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, or fuzzy or unsubstantial image; in optics, photography, and cinematography especially, a flare, secondary image, or spurious signal.