canal

(astronomy) an indistinct surface feature of Mars once thought to be a system of channels; they are now believed to be an optical illusion

a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance; "the tear duct was obstructed"; "the alimentary canal"; "poison is released through a channel in the snake's fangs"

long and narrow strip of water made for boats or for irrigation

provide (a city) with a canal