olfactus

Olfactus is a Latin term historically used to denote the sense of smell or the act of perceiving odors. In classical Latin, olfactus can function as a noun or as a participial adjective, and it forms the root of many modern terms related to smell. In English, the related root olfact- appears in words such as olfactory and olfaction, which derive from this Latin lineage.

In biological and medical contexts, olfaction refers to the sensory process that detects volatile chemical compounds called odorants. Odorants are perceived by olfactory receptor neurons located in the olfactory epithelium inside the nasal cavity. These receptors send signals through the olfactory nerve (cranial nerve I) to the olfactory bulb and onward to higher brain regions, including the piriform cortex and limbic system, enabling the recognition, discrimination, and emotional association of smells.

Clinical relevance includes a range of olfactory disorders. Anosmia is the complete loss of smell, while hyposmia denotes a reduced sensitivity to odors. Causes span upper respiratory infections, nasal and sinus disease, head trauma, and neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease. Aging can also affect olfactory function. Research in this field explores receptor diversity, neural pathways, and connections between smell, flavor perception, memory, and mood.

Etymology and usage: while olfactus appears in historical Latin texts, modern scientific language typically uses olfaction or olfactory to describe the sense of smell and related structures. The term olfactus remains primarily of historical or linguistic interest outside contemporary usage.

See also: olfactory system, olfaction, olfactory receptor.