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endocrine gland n.
Any of various ductless glands, such as the thyroid, adrenal, or pituitary, having hormonal secretions that pass directly into the bloodstream. Also called ductless gland.
any of the systems found in animals for the production of hormones, substances that regulate the functioning of the organism. Such a system may range, at its simplest, from the neurosecretory, involving one or more centres in the nervous system, to the complex array of glands found in the human endocrine system.