Definitions of canal:

• noun:   long and narrow strip of water made for boats or for irrigation
• noun:   (astronomy) an indistinct surface feature of Mars once thought to be a system of channels; they are now believed to be an optical illusion
• noun:   a bodily passage or tube lined with epithelial cells and conveying a secretion or other substance

  Example: "The alimentary canal"

• verb:   provide (a city) with a canal
• name:  A surname (very rare: popularity rank in the U.S.: #34105)