n. 1. any language designed for use in situations in which natural language is unsuitable for the required precision, as in formal logic or in computer programs. The symbols and formulae of such a language stand in precisely defined syntactic and semantic relationships. 2. (Logic) a formal system for which an interpretation is provided. What distinguishes a formal language from a mere formal calculus is that the semantics enable us to regard the former as about some subject matter. See also structure. Compare logistic system.