STRING-DOWNCASE

in a given string, turn upper-case characters into lower-case 
Major Section:  PROGRAMMING

For a string x, (string-downcase x) is the result of applying char-downcase to each character in x.

The guard for string-downcase requires its argument to be a string containing only standard characters.

String-downcase is a Common Lisp function. See any Common Lisp documentation for more information.