$re = '/(?<=amod\().+?(?=-)/m';
$str = 'root(ROOT-0, love-2) s1\', \'amod(perve-5, good-4) s2
advmod(love-2, thanks-12) s3\', \'amod(mags-16, glossy-15) s4';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php