The term 'HIPBONE' is a prefix that can be used to form several words. The four words formed by the prefix are ILIA (4 letters), ILIAL (5 letters), ILIAC (5 letters), and ILIUM (5 letters). Additionally, ECO (3 letters) is also formed by the prefix. All of these words refer to parts of the human body, specifically the HIPBONE or pelvic bone. ILIA refers to the ILIUM, which is the uppermost and largest part of the HIPBONE. ILIAL refers to the ilial crest, which is a ridge on the ILIUM. ILIAC refers to the ILIUM and ischium, which are two parts of the HIPBONE. Lastly, ILIUM refers to the ILIUM alone. ECO refers to the iliac fossa, which is a depression in the HIPBONE.