Noun, pl. glands
1. An organ in an animal’s body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). (wikipedia.org)
2. Organ specialised for secretion by the infolding of an epithelial sheet.
The secretory epithelial cells may either be arranged as an acinus with a duct or as a tubule. Glands from which release occurs to a free epithelial surface are exocrine, those that release product to the circulatory system are endocrine glands. (biology-online.org)
3. Any of various organs that synthesize substances needed by the body and release it through ducts or directly into the bloodstream. (wordnetweb.princeton.edu)
1. A secretory structure on the surface of an organ. (wiktionary.org)