my @terms = sort { length $b <=> length $a } ('lymph', 'lymph node');
my @text = ('right lymph node', 'lymph fluid');
my %results;

foreach my $term (@terms) {
	$results{$term} = 
		(grep /\b$term\b/, @text);		# find matches
	@text = grep !/\b$term\b/, @text;		# remove matches
}

foreach (keys %results) {
	print "$_:\t", $results{$_}, "\n";
}