(idiomatic, law) A legally enforceable, but incompletely specified, agreement between parties that identifies the fundamental terms that are intended to be or are agreed upon.

(idiomatic, rhetoric, logic, linguistics) A type of tautology in which an item is explained in terms of the item itself, only put in different (usually more abstract) words.

(economics) A theory in economics that states that an increase or decrease in income induces a corresponding but magnified change in investment.

(software, object-oriented programming) A software design principle, stated as "Don't call us, we'll call you", that assists in the development of code with high cohesion and low coupling that is easier to debug, maintain and test.

(logic) The principle or axiom of classical logic and some other logical systems stating that if a contradiction or a false proposition is proven to be true, then it proves that everything is true. In symbols: ⊥→P

(biochemistry, archaic) Any of a class of substances found ready-formed in animal and vegetable tissues, and separable by chemical analysis, such as albumin, sugar, collagen, fat, etc.

The claim that something good will turn up, especially when used to justify optimism. / The claim that financial surplus is success and debt is failure.

(psychology, psychoanalysis, Freudianism, often hyphenated when used attributively) The principle that human decisions and behavior are strongly motivated by the instinctual desire of the id, arising in infancy, to experience pleasure and avoid pain.

(psychology, psychoanalysis, Freudianism, often hyphenated when used attributively) The mental mechanism which guides a person, as he or she matures, in adapting to and coping with the real, external world, by suppressing or deferring the childish gratification-seeking desires of the id.

The philosophical notion that an item drawn at random from one of several sets or categories is more likely to come from the most numerous category than from any of the others.