(1):
(n.) A concave cut made in the teeth of some saw blades.
(2):
(n.) The tube by which food and drink are carried from the pharynx to the stomach; the esophagus.
(3):
(n.) Something shaped like the food passage, or performing similar functions
(4):
(n.) A channel for water.
(5):
(n.) A preparatory cut or channel in excavations, of sufficient width for the passage of earth wagons.