Do you know ghouls from goblins and ghosts?
mid-14c., "to form a mental image of," from Old French imaginer "sculpt, carve, paint; decorate, embellish" (13c.), from Latin imaginari "to form a mental picture to oneself, imagine" (also, in Late Latin imaginare "to form an image of, represent"), from imago (see image). Sense of "suppose" is first recorded late 14c. Related: Imagined; imagining.