SHEMIM / Research / Glossary

Scent, Defined

A Glossary of Smell

Plain definitions of the terms behind SHEMIM’s research — each linked to the page that explains it in full.

Olfaction
The sense of smell — detecting airborne molecules through olfactory receptors and reading them as scent. Read more →
Olfactory receptor (OR)
A protein that binds odor molecules. Humans have close to 1,000 OR genes — the largest gene family in the genome — of which roughly 400 are functional. Read more →
Combinatorial code
How smell achieves its range: each odor switches on a particular combination of receptors, so a few hundred receptors can distinguish a vast world of smells. Read more →
Ectopic (extra-nasal) olfactory receptor
An olfactory receptor expressed outside the nose — in skin, gut, kidney, heart and blood — where it reads the body’s own chemistry rather than the air’s. Read more →
GPCR
G-protein-coupled receptor — the large receptor class olfactory receptors belong to, and the target of about a third of all approved medicines. Read more →
Chemoreception
Sensing the chemical environment. The most ancient form of perception, shared across every kingdom of life. Read more →
Volatilome
The complete set of volatile molecules a body emits — the volatile fraction of the metabolome — carried in breath and on the skin. Read more →
VOC (volatile organic compound)
A small, easily evaporated carbon molecule. The breath and skin release hundreds, reflecting the body’s metabolism. Read more →
FeNO
Fractional exhaled nitric oxide — a standard clinical breath test that reads airway inflammation directly from the breath. Read more →
Chemosignal
A chemical cue carried in body odor that conveys information — such as emotion, identity or kinship — to another person. Read more →
Pheromone
A species-wide chemical signal that evolved to carry a specific message. Despite popular belief, no human pheromone has ever been validated. Read more →
Anosmia / Hyposmia
Total (anosmia) or partial (hyposmia) loss of smell — an early sign of conditions from Parkinson’s to infection. Read more →
2-Nonenal
An aldehyde that appears in body odor after roughly age forty and rises with age — the chemistry behind a scent shifting over a lifetime. Read more →
ABCC11
A gene whose common variant determines a person’s body-odor type — and, by the same switch, whether earwax is wet or dry. Read more →
Skin microbiome
The community of bacteria living on the skin that actually produce body odor, by cleaving odorless precursors in sweat. Read more →
Evidence tier
SHEMIM’s reader-facing label for how settled a claim is — from Established (robust, peer-reviewed), through Documented · early and Emerging (real but preliminary), to open questions held openly — shown on every load-bearing statement so evidence is never blurred with inference. Read more →

Every term, traceable to evidence.

SHEMIM’s research is organised so each idea can be followed to its source and its evidence tier.