See the current Perl documentation for quotemeta.
Here is our local, out-dated (pre-5.6) version:
quotemeta - quote regular expression magic characters
Returns the value of
EXPR with all non-alphanumeric characters backslashed.
(That is, all characters not matching
/[A-Za-z_0-9]/ will be preceded by a backslash in the returned string, regardless of any
locale settings.) This is the internal function implementing the
\Q escape in double-quoted strings.
EXPR is omitted, uses