What's the "een" in Halloween?
late 14c., "intercalation of days into a calendar," from Old French embolisme, from Late Latin embolismus "insertion of days in a calendar to correct errors," from Greek embolimos, embolme "insertion," or embolos "a plug, wedge" (see embolus). Medical sense of "obstruction of a blood vessel" is first recorded in English 1855.
embolism em·bo·lism (ěm'bə-lĭz'əm)
The obstruction or occlusion of a blood vessel by an embolus.
An obstruction or occlusion of a blood vessel by an air bubble, a detached blood clot, or a foreign body.