Diapsida diapsid • diapsidan · · · Info · Definitions · Characters · · Diapsida · · Text Latin · · Script 8 · · Length Definitions · · · (noun) used in former classifications to include all living reptiles except turtles; superseded by the two subclasses Lepidosauria and Archosauria. Synonyms: subclass Diapsida. · · Noun Definition 1 Characters · · D latin capital letter d U+0044 a latin small letter a U+0061 d latin small letter d U+0064 i latin small letter i U+0069 p latin small letter p U+0070 s latin small letter s U+0073