Do you know ghouls from goblins and ghosts?
1560s, "wild, unruly" (originally in reference to hawks), from Middle French haggard, probably from Old French faulcon hagard "wild falcon," literally "falcon of the woods," from Middle High German hag "hedge, copse, wood," from Proto-Germanic *hagon-, from PIE root *kagh- "to catch, seize;" also "wickerwork, fence" (see hedge). OED, however, finds this whole derivation "very doubtful." Sense perhaps reinforced by Low German hager "gaunt, haggard." Sense of "with a haunted expression" first recorded 1690s, that of "careworn" first recorded 1853. Sense influenced by association with hag. Related: Haggardly; haggardness.