Ghost

The word ghost has its origins in the Proto-Indo-European (PIE) root gheis (excitement, amazement, fear), the source of Proto-Germanic gaistaz (in turn, the source of Old Saxon gest, Dutch geest, German Geist, all meaning spirit or ghost; in particular, the disembodied spirit of a dead person.
 
From these Germanic sources comes Old English gast or gaest (breath; good or bad spirit, angel, demon; person, man, human being; especially as used in the Biblical sense to mean soul, spirit, life) and Old English gaestan (to terrify).
 
Ghost, as an English term meaning the spirit of a dead person wandering among the living, haunting them, is from the late 14th century. Sounds ghastly.
 
A poltergeist (a noisy spirit or ghost which makes its presence known by noises) is from 1838, from German Poltergeist (literally, ‘noisy ghost’).
 
The words aghast and ghastly (terrified, filled with frightened amazement), from around 1300, are from Middle English agasten (to frighten) and Old English gaest (ghost).
 
In brief, the word ghost has Germanic origins. The related Latin term is spiritus (spirit).
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
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