'anapsidan' originates from New Latin, specifically the word 'Anapsida,' where 'an-' meant 'without' and 'apsis' meant 'arch' or 'loop,' referring to the lack of temporal openings in the skull.

'Anapsida' was adopted in scientific classification in the late 19th century and eventually became the modern English word 'anapsidan' as both a noun and adjective.

Initially, it meant 'without arch' in reference to skull structure, and over time it evolved into its current meaning of 'relating to or being a reptile with a skull lacking temporal openings.'