Which term describes something related to the sense of smell?

The term that describes something related to the sense of smell is olfactory. This term is derived from the Latin word "olfacere," which means "to smell." The olfactory system is crucial for detecting and identifying odors, playing a significant role in taste and the overall sensory experience. This system includes the olfactory bulb, receptors, and pathways that contribute to our perception of smell.

The other terms do not relate to the sense of smell. Ophthalmology pertains to the study of the eyes and vision, oliguria refers to the production of abnormally small amounts of urine, and an ombudsman is an official appointed to investigate individuals' complaints against maladministration, often in government or organizations. Thus, olfactory is the correct choice as it specifically pertains to the sense of smell.