What does cortisol mean?
Cortisol is a steroid hormone — specifically a glucocorticoid — produced by the adrenal glands, two small structures sitting atop the kidneys. It plays a central role in the body's response to stress: when the brain perceives a threat, it signals the adrenal glands to release cortisol into the bloodstream, raising blood sugar, sharpening attention, and suppressing nonessential processes like digestion and inflammation. Beyond its famous role as the 'stress hormone,' cortisol helps regulate metabolism, blood pressure, the immune system, and the natural sleep-wake cycle, with levels normally peaking shortly after waking and falling through the day. In medicine, cortisol is measured to diagnose conditions such as Cushing's syndrome and adrenal insufficiency. Because chronic stress can keep cortisol persistently elevated, it has become a staple term in discussions of health and wellbeing, where it carries connotations of imbalance and burnout.
nounA steroid hormone produced by the adrenal cortex that regulates metabolism, immune response, and the body's reaction to stress.
- A glucocorticoid hormone secreted by the adrenal cortex, involved in stress response, metabolism, blood pressure, and immune function.
"Chronic stress kept her cortisol levels elevated for months, leaving her exhausted."
"The doctor ordered a blood test to measure his morning cortisol."
"Meditation can help lower cortisol, the hormone released during stressful moments."
Rarely pluralized in practice; the plural appears mainly in technical contexts referring to distinct molecular forms or variants of the hormone.
"The assay detected several different cortisols in the sample."
Nicknamed the 'stress hormone,' cortisol is also what wakes you up each morning — your body releases a surge of it just before you open your eyes.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cortisol
Cortisol was named in the twentieth century following the identification of adrenal hormones. It derives from 'cortex,' the Latin word for bark or outer rind, referring to the outer layer of the adrenal gland from which it is secreted; the suffix '-ol' indicates its alcohol (hydroxyl) chemical structure. Its close relative cortisone shares the same root and was coined around the same period, alongside other corticosteroids built on the same Latin root.
How cortisol is actually used
Cortisol is primarily used in medical, scientific, and health contexts. It is frequently discussed in wellness media regarding stress, sleep, and weight, where 'high' or 'low' cortisol often carries connotations of imbalance or poor health. The adjective form is typically expressed via compounds such as 'cortisol level.'
Easily confused with cortisol
Cortisol is the active hormone naturally produced by the body, while cortisone is an inactive precursor converted to cortisol in the liver and used as a medication.