1.  the principles forming the basis for the human ability to understand language. [PJC]

2.  the general properties and constraints common to all human languages; also, the study of such principles. [PJC]

coordinated universal time, descriptive grammar, generative grammar, grammar, grammar school, linguistic universal, prescriptive grammar, rule of grammar, universal, universal agent, universal donor, universal gas constant, universal gravitational constant, universal joint, universal product code, universal proposition, universal quantifier, universal resource locator, universal set, universal solvent, universal suffrage, universal time, universal veil