Lambda abstraction

A lambda abstraction is a lambda expression. It is expressed in the language of lambda calculus. A lambda abstraction is to a functional programming language such as Scheme what pseudo-code is to an imperative programming language.

More specifically, a lambda abstraction is a lambda expression with no free variables: all its variables are bound by some lambda. E.g. f (f (f x)) is a concrete expression, whereas &lambdaf. &lambdax. f (f (f x)) is an abstract lambda expression.