1. A property holding of a theory when proves every formula in its respective language, i.e., when is the language. For example, because classical logic is explosive, the deductive closure of the set is trivial. Because trivial theories are by definition complete, triviality is also known as over-completeness.
2. Describes a consequence relation (either syntactic or semantic) such that for all sets of formulae drawn from its respective language, holds, i.e., the trivial logic.