What is the medical term for the waist area indicated by "pelv/o"?

The term "pelv/o" is derived from the Latin word "pelvis," which refers to the bony structure at the base of the spine, connecting the trunk and the legs. In medical terminology, "pelv/o" specifically indicates the pelvic region, which encompasses the area surrounding the pelvis. This region is crucial in various medical contexts, including anatomy, obstetrics, and urology.

Understanding that "pelvis" refers to this specific bony structure and its associated anatomical area makes it clear why this choice is the correct answer. The other terms, while related to different parts of the body, denote distinct anatomical regions or structures. "Perineum," for example, refers to the area between the anus and the genitals, while "pelvis cavity" is not a standard term used in medical nomenclature, and "pectoral" refers to the chest area. Thus, "pelvis" is the precise term that correlates with the root "pelv/o."