I went down a bit of a linguistic rabbit hole today. One of the FB groups I’m on posted “Why do we say Holy Ghost? Is it a ghost?” After the first minute of smacking my head, I started really looking into the question. Ghost is an English word of Germanic origin, which is used to translate spiritus from latin into old English. It’s first used in Old English as such: sē hālga gāst is Old English for “The Holy Ghost”. Spirit didn’t enter English as a translation for spiritus until the Middle English Period (after the Norman Conquest, when the Normans brought more French and Latinate words into English). Ghost and geist are direct cognates, from English and German respectively. Geist has a meaning of spirit in the supernatural sense, as well as the meaning of apparition and of something having a frightening appearance. It also has a sense of furor or agitation, a sort of ecstasy. Thus, a sense of being filled ‘with the Holy Ghost’ carries a sense of ecstatic experience.