A SHAPELY CATEGORY
'(<a href="http://www.j-archive.com/media/2007-12-04_J_30.jpg" target="_blank">Kelly of the Clue Crew points out a four-sided shape on the monitor.</a>)  In geometry, I'm sure you've come across this shape: it's a plane figure with 2 parallel & 2 non-parallel sides'
a trapezoid