The term 'hormone regulator' refers to a GLAND, which is an organ in the body that produces hormones. Hormones are chemical messengers that help regulate various bodily functions, such as metabolism, growth, and reproduction. The GLAND responsible for hormone regulation is the endocrine GLAND, which secretes hormones into the bloodstream. These hormones then travel throughout the body, where they interact with target cells to produce specific effects. Endocrine glands include the pituitary, thyroid, and adrenal glands, among others.