one of polygons

SQUARE
DECAGON
HEXAGON
NONAGON
OCTAGON
RHOMBUS
PENTAGON
RHOMBOID
TRIANGLE
RECTANGLE
TRAPEZOID
PARALLELOGRAM
QUADRILATERAL
List of words for the clue one of polygons from the crossword:
SIDED OPERA ERA ACE ARIA STAR IDOL LIAR ASIA ERIE ODE EGO TREE ISLE ELI ACRE SEN SEA