just a quick stab at this one :

perl -e 'chomp(@l=(<*>));open(FH,"<test.txt") or die;while(<FH>){for $
+w(@l){/\b$w\b/ ? print: next}}'
[download]

does this do all that you want? or is there a chance that you would need to manipulate/search through more than one line at a time?