Simplified Common Lisp reference
Symbol class: Functions, Evaluation, Flow Control, Definitions and Syntax
Symbol type: function
applyfnargs(zero or more) => value
Argument description:
fn a function designator
args call arguments

APPLY function call supplied function with specified arguments. Argument list is constructed as (append (butlast args) (first (last args))). Note that there is limitation of maximal number of arguments, see CALL-ARGUMENTS-LIMIT constant. See also FUNCALL, LAMBDA.

(apply #'+ 1 2 3 '(4 5 6)) => 21
(apply #'sin '(1.0)) => 0.84147096
(apply #'sin 1.0 nil) => 0.84147096
Function indexFull documentation for apply (HyperSpec)