pelvis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A basin-shaped structure of the skeleton of many vertebrates, composed in humans of the hipbones on the sides, the pubis in front, and the sacrum and coccyx behind, that rests on the lower limbs and supports the spinal column.
• noun The cavity formed by this structure.

from The Century Dictionary.

• noun A bony basin forming the most inferior of posterior one of the three great cavities—thoracic, abdominal, and pelvic—of the trunk of most terrestrial vertebrates.
• noun Hence Some pelviform structure or cuplike part.
• noun [capitalized] A genus of mollusks.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Anat.) The pelvic arch, or the pelvic arch together with the sacrum. See Pelvic arch, under pelvic, and sacrum.
• noun (Zoöl.) The calyx of a crinoid.
• noun (Anat.) the basinlike cavity into which the ureter expands as it joins the kidney.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun anatomy The large compound bone structure at the base of the spine that supports the legs. It consists of hip bone, sacrum and coccyx.
• noun anatomy A funnel-shaped cavity, especially such a cavity in the kidney into which urine passes towards the ureter

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a structure shaped like a funnel in the outlet of the kidney into which urine is discharged before passing into the ureter
• noun the structure of the vertebrate skeleton supporting the lower limbs in humans and the hind limbs or corresponding parts in other vertebrates