rhombus

noun

1. A parallelogram having all sides of equal length.
2. In early Greek religion, an instrument whirled on the end of a string similar to a bullroarer.
3. Any of several flatfishes, including the brill and turbot, once considered part of the genus Rhombus, now in Scophthalmus.
4. Snails, now in genus Conus or family Conidae.