Simplified Common Lisp reference
Symbol class: Conses, Lists and related functions
Symbol type: function
secondlist => value
Argument description:
list cons or full list

SECOND function returns second element of list, that is car part of cdr part of its cons cell. SECOND is identical to CADR.

(second '(1 2 3)) => 2
(second (cons 'a (cons 'b 'c))) => B
Function indexFull documentation for second (HyperSpec)