c:\@Work\Perl\monks>perl -wMstrict -le
"for my $str (qw(
   feed feeder feed001 xfeed001x  fee fee001 xfeex --fee-- fe xxx 001
   )) {
   print qq{'$str' -> },
     $str =~ m{ feed [[:alnum:]]* }xms ? '' : 'NO', ' match';
   }
"
'feed' ->  match
'feeder' ->  match
'feed001' ->  match
'xfeed001x' ->  match
'fee' -> NO match
'fee001' -> NO match
'xfeex' -> NO match
'--fee--' -> NO match
'fe' -> NO match
'xxx' -> NO match
'001' -> NO match