cryp·to·perthite \|kriptō+\noun (-s) Etymology: International Scientific Vocabulary crypt- + perthite; originally formed as German kryptoperthit : a perthite with lamellae of submicroscopic dimensions, such lamellae being observable by X-ray diffraction or by the electron microscope • cryp·to·perthitic\| ̷ ̷ ̷ ̷+\adjective