DB<101> s/(\d)\w\w /$1 / for @a=("December 14th 2012", "December 21st 2012" , "December 22nd 2012")
 => ""
 
  DB<102> @a
 => ("December 14 2012", "December 21 2012", "December 22 2012")

##</code><code>##

  DB<126> map {/^(\w+ \d\d?)\w\w( \d\d\d\d)$/; "$1$2"} "December 1th 2012", "December 21st 2012" , "December 22nd 2012"
 => ("December 1 2012", "December 21 2012", "December 22 2012")