cal·li·pyg·i·an 
(kăl′ə-pĭjē-ən) also cal·li·py·gous (-pīgəs)
(kăl′ə-pĭjē-ən) also cal·li·py·gous (-pīgəs)adj.
Relating to or having buttocks that are considered beautifully proportioned.
[From Greek kallipugos : kalli-, beautiful (from kallos, beauty) + pugē, buttocks.]