1. 血流にホルモンを直接分泌する内分泌系の腺の総称(any of the glands of the endocrine system that secrete hormones directly into the bloodstream)
2. 分泌液が特殊な効果を及ぼす組織へ血液を通じて伝達される内分泌線の分泌液(the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect)