c:\@Work\Perl>perl -wMstrict -le
"use Data::Dump;
 ;;
 my @cleanwords = qw(hut Hat foo HIC);
 my @allwords   = qw(hit Het HAT HiC hAc hoc);
 ;;
 my %dict =
   map { $_ => 1 }
   map canonicalize($_),
   @allwords
   ;
 dd \%dict;
 ;;
 for my $word (@cleanwords) {
   my $common = canonicalize($word);
   printf qq{word '$word' %sin dictionary \n},
     exists $dict{$common} ? '' : 'NOT ';
   }
 ;;
 sub canonicalize { return lc $_[0]; }
"
{ hac => 1, hat => 1, het => 1, hic => 1, hit => 1, hoc => 1 }

word 'hut' NOT in dictionary
word 'Hat' in dictionary
word 'foo' NOT in dictionary
word 'HIC' in dictionary