Definition of ptychodont in US English:

ptychodont

adjective

  • Of a tooth: having a series of ridges that acts as a grinding surface; (originally specifically of a mammalian molar) having the crown folded at the sides, with the folds often crossing the crown. Of a dentition: consisting of such teeth. Now rare.

noun

  • An animal with ptychodont or similar teeth; specifically a fossil shark of the Cretaceous family Ptychodontidae, with teeth that have a series of parallel folds adapted for crushing shells.

Origin

Late 19th century; earliest use found in Proceedings of the Academy of Natural Sciences of Philadelphia. From ancient Greek πτυχή fold + -odont. In later specific sense of the noun, after scientific Latin Ptychodontidae, family name.