1. a model, pattern, or representative example, as of the functions and interrelationships of a process, a behavior under study, or the like.

2. a set of assumptions, attitudes, concepts, values, procedures, and techniques that constitutes a generally accepted theoretical framework within, or a general perspective of, a discipline.

3. an experimental design or plan of the various steps of an experiment.

4. in grammar, the set of all the inflectional forms of a word.