What does endocrine mean?
The adjective "endocrine" describes the network of ductless glands that release hormones directly into the bloodstream to regulate bodily processes such as growth, metabolism, reproduction, and mood. Key endocrine glands include the pituitary, thyroid, adrenal glands, and pancreas. The word derives from Greek roots meaning "secreting inward," which captures the defining feature of these glands: unlike exocrine glands, which discharge their products through ducts onto a surface, endocrine glands send their secretions internally via the blood. In modern usage, "endocrine" appears most often in scientific phrases such as "endocrine system," "endocrine disorder," and "endocrine disruptor" — the last referring to chemicals that interfere with hormonal function. It is a formal, technical term belonging to medicine and biology, but it has become increasingly familiar to the general public through discussions of hormonal health and environmental science.
Relating to glands that secrete hormones directly into the bloodstream, or to the system formed by such glands.
"Adrenaline is produced by the adrenal glands, part of the body's endocrine system."
Almost always used attributively before a noun, as in "endocrine gland" or "endocrine function."
(Chiefly in older medical usage) An endocrine gland or an endocrine secretion.
"Early twentieth-century physiologists classified each ductless gland as a distinct endocrine."
This nominal use is now rare; "endocrine gland" or "hormone" is preferred in contemporary writing.
The word 'endocrine' literally means 'secreting inward' in Greek — a perfect description of glands that whisper their chemical messages straight into your bloodstream.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of endocrine
"Endocrine" was coined in the early 20th century from the Greek elements "endon" (within) and "krinein" (to separate or secrete), literally meaning "secreting inward." It emerged as scientists came to understand that certain glands release their products directly into the blood rather than through ducts, giving rise to the new science of endocrinology around the first decade of the 1900s. The same Greek root "krinein" appears in related terms such as "exocrine," its functional opposite, and in more distant relatives like "criterion" and "critic."
Related word forms
How endocrine is actually used
"Endocrine" is a technical term used chiefly in medical, scientific, and health contexts. It functions almost exclusively as an attributive adjective (as in "endocrine gland"), rarely appearing predicatively. The noun "endocrine" itself is uncommon outside older medical usage referring to an endocrine gland or secretion.
Easily confused with endocrine
Exocrine glands release their secretions through ducts to a surface (such as sweat or digestive glands), whereas endocrine glands secrete hormones directly into the blood.
Endogenic means originating from within a system or organism (often in geology), while endocrine specifically concerns hormone-secreting glands.