Another option is to arrange your search terms into a sorted list: 
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";
}

[download]
This is likely less expensive with more search terms than building a large regexp, but the grep unfound operation may not help.

In reply to Re: How do I match for several strings, matching the longest string first? by chromatic
in thread How do I match for several strings, matching the longest stringfirst? by g man

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