Final answer:
The combining form 'phren/o' can denote both the diaphragm and the mind. It is derived from Greek and is used in medical terminology for both anatomical references to the diaphragm and in historical contexts relating to the mind.
Step-by-step explanation:
The combining form that can mean either diaphragm or mind is phren/o. This form is derived from the Greek word phren, which historically referred to both the physical diaphragm as well as the concept of the mind. For example, phrenology (a now outdated field) was the study of the shape of the skull as it was believed to relate to the functions of the mind. When using it to refer to the diaphragm, terms like phrenic nerve, which stimulates the diaphragm, can be generated.