contains the words "apple", "cherry" and "blossom".

Actually, there is much more ...

#!/usr/bin/perl -w
use strict;

my $search_word = shift
   or die "search word required\n";

my @words = ();
my $count = 0;
open WORDS, "/usr/share/dict/words"
     or die "can't open words file\n";
while (<WORDS>) {
    chomp;
    printf "%3d %s\n", ++$count, $_ if $search_word =~ /$_/i;
}
close WORDS;
[download]

And here is the result:

$ perl wsearch.pl owijfwapplelaskfiwejfcherryalkfwiofwfblossomowiejf
  1 Al
  2 apple
  3 as
  4 ask
  5 blossom
  6 cherry
  7 err
  8 he
  9 her
 10 Herr
 11 Io
 12 Los
 13 loss
 14 mow
 15 of
 16 so
 17 we

I know it's a brute force, but it takes less than half second to give this result.

Consider that Perl RegEx engine is using a Boyer-Moore search algorithm, which is probably the fastest one available for text matching.