tet·ra·gon 
(tĕtrə-gŏn′)
(tĕtrə-gŏn′)n.
A polygon with four sides and four angles; a quadrilateral.
[Late Latin tetragōnum, from Greek tetragōnon, square, from neuter of Greek tetragōnos, having four angles : tetra-, tetra- + -gōnos, angled; see -GON.]
te·trago·nal (tĕ-trăgə-nəl) adj.
te·trago·nal·ly adv.
- lower
- Lower 48
- lower 48
- lower bound
- Lower California
- Lower California
- Lower Canada
- Lower Carboniferous
- lowercase
- lowercase letter
- lower class
- lower-class
- lowerclassman
- lower criticism
- Lower Egypt
- lower esophageal sphincter
- Lower Forty-Eight
- loweringly
- Lower Michigan
- Lower Michigan
- lowermost
- Lower Palatinate
- Lower Peninsula
- Lower Rhine
- Lower Sorbian