A secretion is a substance made and released by a living thing, like when your skin sweats.

Secretions don't have to do with secrets, but with secreting: synthesizing and then producing a substance. A machine can't make a secretion — only living things can. Many secretions are harmless, while others are dangerous to other animals. For example, the secretions of some frogs are a type of poison. Some secretions stay within an animal, like the bile secreted by our livers. Saliva is another secretion. The word comes from the Latin root secretionem, "separation."

Definitions of secretion
  1. noun
    the organic process of synthesizing and releasing some substance
    synonyms: secernment
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    the secretion of milk
    excessive secretion
    the secretion of saliva
    excessive flow of saliva
    type of:
    biological process, organic process
    a process occurring in living organisms
  2. noun
    a functionally specialized substance (especially one that is not a waste) released from a gland or cell
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    ganoin, ganoine
    shiny substance that resemble enamel and is secreted by the corium of certain fishes (especially ganoid fishes) and composes the outer layer of their scales
    lachrymal secretion, lacrimal secretion
    saline fluid secreted by lacrimal glands; lubricates the surface of the eyeball
    perspiration, sudor, sweat
    salty fluid secreted by sweat glands
    endocrine, hormone, internal secretion
    the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
    intestinal juice
    secretions by glands lining the walls of the intestines
    autacoid, autocoid
    any physiologically active internal secretion especially one of uncertain classification
    synovia, synovial fluid
    viscid lubricating fluid secreted by the membrane lining joints and tendon sheaths etc.
    mucous secretion, mucus
    protective secretion of the mucus membranes; in the gut it lubricates the passage of food and protects the epithelial cells; in the nose and throat and lungs it can make it difficult for bacteria to penetrate the body through the epithelium
    saliva, spit, spittle
    a clear liquid secreted into the mouth by the salivary glands and mucous glands of the mouth; moistens the mouth and starts the digestion of starches
    the oily secretion of the sebaceous glands; with perspiration it moistens and protects the skin
    royal jelly
    a secretion of the pharyngeal glands of bees that is fed to very young larvae and to bees destined to be queens
    an odorous glandular secretion from the male musk deer; used as a perfume fixative
    a sweet liquid secretion that is attractive to pollinators
    a chemical substance secreted externally by some animals (especially insects) that influences the physiology or behavior of other animals of the same species
    ACTH, adrenocorticotrophic hormone, adrenocorticotrophin, adrenocorticotropic hormone, adrenocorticotropin, corticotrophin, corticotropin
    a hormone produced by the anterior pituitary gland that stimulates the adrenal cortex
    Adrenalin, adrenaline, epinephrin, epinephrine
    a catecholamine secreted by the adrenal medulla in response to stress (trade name Adrenalin); stimulates autonomic nerve action
    GI hormones, gastrointestinal hormone
    hormones that affect gastrointestinal functioning
    a hormone secreted by the pancreas; stimulates increases in blood sugar levels in the blood (thus opposing the action of insulin)
    gonadotrophic hormone, gonadotrophin, gonadotropic hormone, gonadotropin
    hormone secreted by the anterior pituitary gland and placenta; stimulates the gonads and controls reproductive activity
    hormone secreted by the isles of Langerhans in the pancreas; regulates storage of glycogen in the liver and accelerates oxidation of sugar in cells
    hormone secreted by the pineal gland
    a hormone that is released by nerve impulses (e.g., norepinephrine or vasopressin)
    Pitocin, oxytocin
    hormone secreted by the posterior pituitary gland (trade name Pitocin); stimulates contractions of the uterus and ejection of milk
    parathormone, parathyroid hormone
    hormone synthesized and released into the blood stream by the parathyroid glands; regulates phosphorus and calcium in the body and functions in neuromuscular excitation and blood clotting
    hormone secreted by the corpus luteum during the last days of pregnancy; relaxes the pelvic ligaments and prepares the uterus for labor
    RH, hypothalamic releasing factor, hypothalamic releasing hormone, releasing factor, releasing hormone
    any of several hormones produced in the hypothalamus and carried by a vein to the anterior pituitary gland where they stimulate the release of anterior pituitary hormones; each of these hormones causes the anterior pituitary to secrete a specific hormone
    STH, growth hormone, human growth hormone, somatotrophic hormone, somatotrophin, somatotropic hormone, somatotropin
    a hormone produced by the anterior pituitary gland; promotes growth in humans
    hormone secreted by the thymus; stimulates immunological activity of lymphoid tissue
    thyroid hormone
    any of several closely related compounds that are produced by the thyroid gland and are active metabolically
    ADH, Pitressin, antidiuretic hormone, vasopressin
    hormone secreted by the posterior pituitary gland (trade name Pitressin) and also by nerve endings in the hypothalamus; affects blood pressure by stimulating capillary muscles and reduces urine flow by affecting reabsorption of water by kidney tubules
    a potent substance that acts like a hormone and is found in many bodily tissues (and especially in semen); produced in response to trauma and may affect blood pressure and metabolism and smooth muscle activity
    phlegm, sputum
    expectorated matter; saliva mixed with discharges from the respiratory passages; in ancient and medieval physiology it was believed to cause sluggishness
    nasal mucus
    dried nasal mucus
    dribble, drivel, drool, slobber
    saliva spilling from the mouth
    tobacco juice
    saliva colored brown by tobacco (snuff or chewing tobacco)
    a white secretion of the sebaceous glands of the foreskin
    leucorrhea, leukorrhea
    discharge of white mucous material from the vagina; often an indication of infection
    sex hormone, steroid, steroid hormone
    any hormone affecting the development and growth of sex organs
    a steroid having androgenic activity; obtained from the cortex of the adrenal gland
    a steroid hormone that is produced by the adrenal cortex of animals; affects functioning of gonads and has anti-inflammatory activity
    any of a group of chemicals including epinephrine and norepinephrine that are produced in the medulla of the adrenal gland
    MSH, melanocyte-stimulating hormone
    a hormone secreted by the anterior pituitary gland that controls the degree of pigmentation in melanocytes
    TSH, thyroid-stimulating hormone, thyrotrophic hormone, thyrotrophin, thyrotropic hormone, thyrotropin
    anterior pituitary hormone that stimulates the function of the thyroid gland
    TRF, TRH, protirelin, thyrotropin-releasing factor, thyrotropin-releasing hormone
    hormone released by the hypothalamus that controls the release of thyroid-stimulating hormone from the anterior pituitary
    type of:
    bodily fluid, body fluid, humor, humour, liquid body substance
    the liquid parts of the body
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