Oxford English Dictionary 2a Something which accurately resembles or represents something else, esp. on a small scale; a person or thing that is the likeness of another. [e.g., a model airplane]
4b Art. An object or figure made in clay, wax, etc., as an aid to the execution of the final form of a sculpture or other work of art . . .
8a A simplified or idealized description or conception of a particular system, situation, or process, often in mathematical terms, that is put forward as a basis for theoretical or empirical understanding, or for calculations, predictions, etc.; a conceptual or mental representation of something.
9a A person, or a work, that is proposed or adopted for imitation; an exemplar. Later also: a person or place on which a fictional character, location, etc., is based.
10 A person or thing eminently worthy of imitation; a perfect exemplar of some excellence.
11a A person or (less commonly) a thing serving as an object to be copied or depicted by an artist, sculptor, etc.; a person employed to pose for this purpose.
model in science: A systematic description of an object or phenomenon that shares important characteristics with the object or phenomenon. Scientific models can be material, visual, mathematical, or computational and are often used in the construction of scientific theories. (http://science.yourdictionary.com/model)