Several words associated with Halloween, such as "trick-or-treat," "boo" and "bogeyman" have their origins in the Scottish language. "Halloween" itself is a Scottish word in origin. Other words associated with the holiday come from other languages, such as early English or Arabic.
"Halloween" is a Scottish shortening of "Allhallow-even," the last night of the Celtic calendar. That night was dedicated to witches. "Jack-o-lantern" was an early modern English colloquial term describing the will-o'-the-wisp phenomenon. It was also the name for a night watchman, referencing his lantern. The term was first used for pumpkin lanterns in 1800s.
"Trick-or-treating" is the English name for guising, a Scottish custom of dressing in costume and doing a card trick or telling a story in exchange for something sweet. Because this was similar to souling, an All Souls Day practice of begging for food in exchange for prayers for the dead, Halloween celebrators eventually adopted the practice by the middle of the 20th century.
According to a Scottish publication in the 1700s, the word "boo" was initially used to frighten children. The sound was attributed to ghosts by the 1800s. "Bogeyman" derives from the Scottish word "bogle," which meant "ghost." "Ghoul" derives from the Arabic word "ghul," which was the name of an evil spirit that robbed graves and consumed corpses.