/ˈiskēəm/
Noun, pl. ischia
1. Forms the lower and back part of the hip bone. Situated below the ilium and behind the pubis, it is one of these three bones whose fusion creates the coxa. The superior portion of this bone forms approximately one third of the acetabulum. It is made up of three portions:
- body of ischium
- superior ramus of the ischium
- inferior ramus of the ischium
(wikipedia.org)
2. The lowest of the three bones that make up each side of the pelvis. (wiktionary.org)
3. The curved bone forming the base of each half of the pelvis. (Google Dictionary)
4. (Entomology) One of the pleurae of an insect. (biology-online.org)
Syn: seat bone, huckle bone, ischial bone
Word origin: From Latin, from Greek iskhion “hip joint,” in plural, “the hips,” probably from iskhi “loin,” of unknown origin.