What is "lambda calculus"

n. (context computing theory English) Any of a family of functionally complete algebraic systems in which lambda expressions are evaluated according to a fixed set of rules to produce values, which may themselves be lambda expressions.

Lambda calculus (also written as λ-calculus) is a formal system in mathematical logic for expressing computation based on function abstraction and application using variable binding and substitution. It is a universal model of computation that can be used to simulate any single-taped Turing machine and was first introduced by mathematician Alonzo Church in the 1930s as part of an investigation into the foundations of mathematics.