An Etymological Dictionary of the German Language/Annotated/Gespenst
Gespenst, neuter, ‘spectre, ghost,’ from Mid High German gespęnste, neuter (gespęnst, gespanst, feminine), ‘enticement, allurement, infernal illusion, ghost,’ Old High German gispanst, feminine, ‘enticement’; the latter meaning is the original one, since Gespenst (see also ab-, widerspenstig), according to its form, is a verbal abstract of an Old Teutonic spanan, ‘to entice.’ Compare Old Saxon and Old High German spanan, ‘to entice, charm,’ Middle High German spanen (compare Greek σπάω).