One of the mysteries of the English language finally explained.

# Definition of *model theory* in English:

## model theory

### noun

1A theory based on or involving a representation or model, whether actual or conceptual.

2The theory of making representational scale models, typically as guides to the behaviour of the object modelled.

3Mathematics and Logic. The theory of mathematical or conceptual models, dealing with their construction, properties, the conditions of their validity, etc.; specifically a branch of mathematical logic dealing with the classification of mathematical structures and their elements in terms of first-order formulae that the elements satisfy.

4A theory that is based on an exemplar or model; a theory that provides an exemplar or model.

**Origin**

Mid 19th century; earliest use found in Jabez Allies (bap. 1787, d. 1856), antiquary. From model + theory.