(anatomy) An organ, such as the heart or colon, that is entirely within the confines of the body.

Alternative spelling of microorganism

plural of micro-organism

plural of umbrella organization

An organization that coordinates the activities of a number of member organisations to promote a common goal.

(law) A law or system of laws which forms the foundation of a government, corporation or other organization's body of rules. A constitution is a particular form of organic law for a sovereign state.

plural of house organ

A person (living or dead) from whom an organ is removed in order to be transplanted into another person. / (chiefly US, slang) A motorcyclist, especially one who does not wear a protective helmet.

An organ of the body which performs a sufficiently important function that damage to the organ can cause death.

plural of vital organ