pelvis

Pelvis is the Latin word for a basin, a wide shallow vessel used for washing. Roman houses had a pelvis in the atrium for collecting rainwater. The word was borrowed into anatomy because the ring of bones at the base of the spine — formed by the ilium, ischium, pubis, and sacrum — resembles a shallow bowl. The anatomical pelvis is a basin that holds the intestines, bladder, and reproductive organs. The metaphor is exact.

The anatomical use of pelvis appears in medical Latin from at least the 16th century. Andreas Vesalius, in De Humani Corporis Fabrica (1543), used the word to describe the bony ring. The term was not new — medieval anatomists had used it — but Vesalius's illustrated anatomy standardized the vocabulary. His detailed engravings of the pelvis showed what words alone could not: the basin shape, the joints, the differences between male and female pelvises.

The pelvis is one of the most sexually dimorphic bones in the human skeleton. A female pelvis is wider and shallower, adapted for childbirth. A male pelvis is narrower and deeper. Forensic anthropologists can determine sex from a pelvis with over 95% accuracy. This difference is why the word pelvis appears in both anatomy textbooks and crime scene reports — it is the bone that tells you who someone was.

The word entered English in the early 17th century, directly from Latin. It replaced no existing English term because English had no word for this specific bone structure before anatomists needed one. The basin metaphor proved durable. Four centuries later, the pelvis is still a basin in every anatomy class in every language that borrowed the Latin term.