orbitoid|ˈɔːbɪtɔɪd| [f.mod.L. orbitoīdes, f.orbita orbit n.; see -oid.] The flat round fossil shell of a Foraminifer of the genus Orbitoides, occurring in tertiary limestones in N. America, etc. 1885Amer.Jrnl.Sc. XXX. 70, I found..a small specimen of an Orbitoid.