It Joins the Upper Leg to the Pelvis

Puzzle 9 of Bucket List Piece of Cake Pack

Question is: It Joins the Upper Leg to the Pelvis

and the answer is: HIPBONE

Word Meaning:

HIP BONE — (anatomy) One of two roughly symmetrical parts of the skeleton, each composed of the fused iliac, ischial, and pubic bones, that together form the sides of the pelvis.

Definitions from Wiktionary.