pentagon

1 ENTRIES FOUND:
pentagon /ˈpɛntəˌgɑːn/ noun
plural pentagons
pentagon
/ˈpɛntəˌgɑːn/
noun
plural pentagons
Britannica Dictionary definition of PENTAGON
1 
[count] mathematics : a flat shape that has five sides and five corners — see picture at geometry
2 
the Pentagon
a  : the building in Washington, D.C., that is the headquarters of the U.S. Department of Defense
b  : the leaders of the U.S. military

— pentagonal

/pɛnˈtægənl̟/ adjective, mathematics