S / sŭpīnĭtas
noun

sŭpīnĭtas

gen. ātis · gender feminine · decl. 3rd
a bending backwards
a bending backwards (very rare).
Lit.: est odiosa omnis supinitas, Quint. 11, 3, 122. —
by extension
Transf.: Planasia (insula) de supinitate sic vocata, its lying flat, flatness, Sol. 3, 2.