- any of various internally secreted compounds, as insulin or thyroxine, formed in endocrine glands, that affect the functions of specifically receptive organs or tissues when transported to them by the body fluids.
- a synthetic substance used in medicine to act like such a compound when introduced into the body.
- any of various plant compounds, as auxin or gibberellin, that control growth and differentiation of plant tissue.
- a chemical substance produced in an endocrine gland and transported in the blood to a certain tissue, on which it exerts a specific effect
- an organic compound produced by a plant that is essential for growth
- any synthetic substance having the same effects
