$re = '/([|@\\\\]+)?([\w]+)/m';
$str = 'meaning
meaning|description
meaning@id
meaning|description@id
|description
|description@id
@id
meaning@id|description
sub1\\|sub2
mea\\|ning|descri\\@ption
mea\\@ning@id
meaning|description@identific\\|\\@ation';
preg_match_all($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