Freebase(0.00 / 0 votes)Rate this definition: Hydroelectricity. Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water.
Definition: Hormones. Hormones. Hormones are chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control how cells and organs do their work. For example, insulin is a hormone that's made by the beta cells in the pancreas.
LINK / CITE ADD TO WORD LIST. noun. The definition of a hormone is a substance formed in an organ or tissue in the body of a plant or animal and then transported by body fluid to another organ or tissue for a specific action.An example of a hormone is estrogen in humans. 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.