Definition of: ghost

(gōst) noun
1. A disembodied spirit.
2. The soul or spirit.
3. A shadow or semblance; slight trace.
4. A spirit of any kind.
5. Optics a A false or secondary image, or a spot of light, as from a defect in a lens or instrument. b In television, a secondary image, appearing as a doubling of the image to the right, caused by reception of a reflected signal a fraction of a second later than the primary image.
6. Obs. The Holy Ghost.
7. U.S. Slang An addict to opium-smoking.
8. Metall. A narrow band of metal on steel ingots or forgings, harder than the adjoining parts; it becomes more evident on machining: also ghost line. See synonyms under SPECTER.
—to give up the ghost. To die.
—v.t. & v.i.
1. To haunt as a ghost.
2. Colloq. To write as a ghost writer. [OE gāst spirit]
—ghost′like′ adjective