A part of the body that performs a specific function. For example, the heart is an organ.

A unique macroscopic (gross) anatomic structure that performs specific functions. It is composed of various tissues. An organ is part of an anatomic system or a body region. Representative examples include the heart, lung, liver, spleen, and uterus.

Anatomical structure, each instance of which has a maximal complement of instances of two or more types of tissue or one or more types of essential morphologic unit, a predominantly bona fide boundary and intrinsic vasculature and neural network. Examples: liver, lung, kidney, stomach, urinary bladder, gall bladder.

Anatomical structure, which consists of the maximal set of organ parts so connected to one another that together they constitute a unit of macroscopic anatomy, structurally distinct from other such units. Together with other organs, an organ constitutes an organ system or a body part. An organ is divisible into organ parts but not organs. Examples: femur, biceps, liver, heart, skin, tracheobronchial tree, sciatic nerve, ovary.

Structure containing more than one cell type, organized to carry out a particular function of the body.

Organ, in biology, a group of tissues in a living organism that have been adapted to perform a specific function. In higher animals, organs are grouped into organ systems; e.g., the esophagus, stomach, and liver are organs of the digestive system. In the more advanced animals, there are usually 10...