Any of various hormones, such as estrogen and androgen, affecting the growth or function of the reproductive organs, the development of secondary sex characteristics, and the behavioral patterns of animals.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.