OED's definitions

Callipygian

Of, pertaining to, or having well-shaped or finely developed buttocks.

From the Greek 'beauty' + 'buttocks', also the name of a famous statue of Venus

1648 Sir T. Browne Pseud. Ep. Calliphygae nd women largely composed behinde.

1800 The Calliphygian Venus

1885 Athenaeum The Calliphygian luxuriance he so deplores

by OED January 7, 2005