lambda

lambda is a Lisp macro in `subr.el'.

(lambda ARGS [DOCSTRING] [INTERACTIVE] BODY)

Return a lambda expression.
A call of the form (lambda ARGS DOCSTRING INTERACTIVE BODY) is
self-quoting; the result of evaluating the lambda expression is the
expression itself. The lambda expression may then be treated as a
function, i.e., stored as the function value of a symbol, passed to
`funcall' or `mapcar', etc.

ARGS should take the same form as an argument list for a `defun'.
DOCSTRING is an optional documentation string.
If present, it should describe how to call the function.
But documentation strings are usually not useful in nameless functions.
INTERACTIVE should be a call to the function `interactive', which see.
It may also be omitted.
BODY should be a list of Lisp expressions.