Definitions
1.NounAnything having the shape of a turtle's back (that is, its shell).
2.NounA convex deck at the bow or stern of a vessel, designed to shed seawater quickly.
3.NounAn armor layout with an armored deck which slopes downwards towards the sides of the ship and connects to the lower edge of the main belt armor, designed to deflect shells striking the ship on trajectories close to horizontal.
4.NounA primitive stone celt of a form suggesting the back of a turtle.
5.NounA library binding of a mass market paperback with a generic hardcover."(The addition of quotations indicative of this usage is being sought:)"
6.NounAny plant of the genus Psathyrotes of annual and perennial forbs and low subshrubs native to dry areas of southwestern North America.