Which term refers to a round opening in a bone?

The term that refers to a round opening in a bone is indeed "foramen." In anatomical terminology, a foramen is defined as a natural opening or passage that allows for the transmission of nerves and blood vessels. The round shape is characteristic of many foramina, such as the foramen magnum at the base of the skull, which allows the spinal cord to connect with the brain. Understanding this term is crucial for comprehending how various structures within the body interact, especially in the context of the skeletal system and its role in protecting and facilitating the function of the nervous system.

While other options listed may refer to openings, they do not specifically denote a round shape or the specific function associated with a foramen. Fissures refer to narrow, slit-like openings, while a hole is a more general term that lacks the precise anatomical definition needed in this context. The term "port" typically relates to an entry point or harbor, which is not used in classical anatomy to describe bone openings.