dead of night; middle of the night; midnight; third quarter of the hour of the ox (2-2:30am, or 3-3:30am)
cursing ritual where one visits a shrine at 2am and nails a doll representing a person to a tree, praying for said person's death
① 暦の上で丑にあたる日。② 夏の土用の丑の日、冬の寒中の丑の日。