$re = '/^(?<!#)(\w+)\s(\w+)\s(\[.*?\])\s/(.+)/$/mu';
$str = '# For more information about CC-CEDICT see:
# http://cc-cedict.org/wiki/
A A [A] /(slang) (Tw) to steal/
AA制 AA制 [A A zhi4] /to split the bill/to go Dutch/
AB制 AB制 [A B zhi4] /to split the bill (where the male counterpart foots the larger portion of the sum)/(theater) a system where two actors take turns in acting the main role, with one actor replacing the other if either is unavailable/
A咖 A咖 [A ka1] /class "A"/top grade/
A圈兒 A圈儿 [A quan1 r5] /at symbol, @/
A片 A片 [A pian4] /adult movie/pornography/';
preg_match_all($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