What is the root word for navel or umbilicus?

The root word for navel or umbilicus is "umbillic/o." This root specifically refers to the area around the navel, also known as the umbilical region. In medical terminology, understanding root words is essential as they lay the foundation for more complex terms and can help in identifying the meanings of related words. In this case, "umbillic/o" accurately conveys the anatomical reference to the umbilicus.

Other options, while they may have their significance in medical terminology, do not pertain to the navel. "Thorac/o" relates to the chest area, "ventr/o" refers to the belly or abdomen, and "atom/o" is associated with atoms or the fundamental structure of matter. These connections highlight the importance of recognizing the specific roots associated with particular body parts or conditions in the study of medical terminology.