caudation
/kɔːˈdeɪʃən/ or /kɒˈdeɪʃən/Definitions
1. noun
A deformity of the spine, in which the lower back is curved outward and the buttocks are more prominent, often caused by a congenital condition or rickets.
“The child was born with caudation, a rare deformity that affected her ability to walk normally.”