my @filesize_names = qw(bit nibble byte kilobyte megabyte gigabyte terabyte petabyte exabyte zettabyte yottabyte);

  my $word = 'fubar';
     $word =~ s/s$//;

  my @short_sizes = apply {$_ =~ s/^(\w)\w{1,}$/$1b/} @filesize_names;

  print Dumper(\@filesize_names);
  print Dumper(\@short_sizes);

  if (grep(lc $word,@short_sizes)) { # even 'fubar' greps
    print "$word grepped!";
    $word = $filesize_names[firstidx { $_ eq lc $word } @short_sizes];
  }

  print $word;