From WordNet (r) 3.0 (2006) [wn]:
canal
n 1: (astronomy) an indistinct surface feature of Mars once
thought to be a system of channels; they are now believed
to be an optical illusion
2: 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" [syn: duct,
epithelial duct, canal, channel]
3: long and narrow strip of water made for boats or for
irrigation
v 1: provide (a city) with a canal [syn: canal, canalize,
canalise]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Canal \Ca*nal"\, n. [F. canal, from L. canalis canal, channel;
prob. from a root signifying "to cut"; cf. D. kanaal, fr. the
French. Cf. Channel, Kennel gutter.]
[1913 Webster]
1. An artificial channel filled with water and designed for
navigation, or for irrigating land, etc.
[1913 Webster]
2. (Anat.) A tube or duct; as, the alimentary canal; the
semicircular canals of the ear.
[1913 Webster]
3. A long and relatively narrow arm of the sea, approximately
uniform in width; -- used chiefly in proper names; as,
Portland Canal; Lynn Canal. [Alaska]
[Webster 1913 Suppl.]
Canal boat, a boat for use on a canal; esp. one of peculiar
shape, carrying freight, and drawn by horses walking on
the towpath beside the canal.
Canal lock. See Lock.
[1913 Webster]