hor·mone (hôr?m?n?)n.1. a. A substance, usually a peptide or steroid, produced by one tissue and conveyed by the bloodstream to another to effect physiological activity, such as growth or metabolism.b. A synthetic compound that acts like a hormone in the body.2. Any of various similar substances found in plants and insects that regulate development.[From Greek horm?n, present participle of horm?n, to urge on, from horm?, impulse; see er- in Indo-European roots.]hor·mon?al (-m??n?l), hor·mon?ic (-m?n??k) adj.hor·mon?al·ly adv.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.hormone (?h??m??n) n1. (Biochemistry) a chemical substance produced in an endocrine gland and transported in the blood to a certain tissue, on which it exerts a specific effect2. (Biochemistry) an organic compound produced by a plant that is essential for growth3. (Biochemistry) any synthetic substance having the same effects[C20: from Greek horm?n, from horman to stir up, urge on, from horm? impulse, assault] hor?monal, hormonic adj hor?monally adv ?hormone?like adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014hor?mone (?h?r mo?n) n. 1. any of various internally secreted compounds formed in endocrine glands that affect the functions of specifically receptive organs or tissues when transported to them by the body fluids. 2. a synthetic substance that acts like such a compound when introduced into the body. 3. any of various plant compounds, as auxin or gibberellin, that control growth and differentiation of plant tissue. [1900?05;