noun
side door; side gate; wicket gate
Refers to a small, secondary entrance, often a side door or wicket gate, typically in traditional Japanese architecture.
庭へはくぐりから入ってください。
Please enter the garden through the side gate.
古い屋敷にはくぐり戸がついていること
Old mansions sometimes have a wicket door.
勝手口 is a kitchen door or back entrance, whereas くぐり is a small gate or door, not necessarily for kitchen use.
Derived from the verb くぐる (to pass through a narrow opening), referring to a small entrance one must duck or squeeze through.