Hormone

n. any of a number of substances which are secreted into the bloodstream by endocrine glands and stimulate particular organs or tissues (Biochemistry)

A hormone (from Greek όρμή - "to set in motion") is a chemical messenger that carries a signal from one cell (or group of cells) to another. All multicellular organisms produce hormones (including plants - see phytohormone). The function of hormones is to carry information to the target cells; the action of hormones is determined by the pattern of secretion and response of the receiving tissue - the signal transduction response.The best-known animal hormones are those produced by endocrine glands of vertebrate animals, but hormones are produced by nearly every organ system and tissue type in a multicellular organism.
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Hormone /hor·mone/ a chemical substance produced in the body which has a specific regulatory effect on the activity of certain cells or a certain [more]Hormone - Community and Resources

Noun
1. the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
(synonym) endocrine, internal secretion
(hypernym) secretion
(hyponym) adrenocorticotropic hormone, adrenocorticotrophic hormone, ACTH, adrenocorticotropin, adrenocorticotrophin, corticotropin, corticotrophin

n. hormone, any of a number of substances which are secreted into the bloodstream by endocrine glands and stimulate particular organs or tissues (Biochemistry)