Synonyms for Pelvis (same or very similar meaning)
WordNet sense 1 (the structure of the vertebrate skeleton supporting the lower limbs in humans and the hind limbs or corresponding parts in other vertebrates):
hip, pelvic arch, pelvic girdle
WordNet sense 2 (a structure shaped like a funnel in the outlet of the kidney into which urine is discharged before passing into the ureter):
renal pelvis
From the ODE community, based on WordNet
add/edit