Callipygian [pron. kalɪˈpɪdʒɪən]
This is a rarely used adjective which originates from the late 18th century meaning having well-shaped buttocks. It is derived from Greek kallipūgos (used to describe a famous statue of Venus), from kallos beauty + pūgē buttocks, + -ian.
How to use it in a sentence:
‘I’m in search of a callipygian woman.’
‘The callipygian figure of Michelangelo’s David never failed to inspire me.’