Archosaur and Diapsid

Archosaur noun - Extinct reptiles including: dinosaurs; plesiosaurs; pterosaurs; ichthyosaurs; thecodonts.

Diapsid and archosaur are semantically related. In some cases you can use "Diapsid" instead a noun "Archosaur".

Diapsid noun - Reptile having a pair of openings in the skull behind each eye.

Archosaur and diapsid are semantically related. Sometimes you can replace term "Archosaur" with "Diapsid", this nouns are similar.