$re = '/^(?!.*\bjacket\b).*\badidas\b.*/m';
$str = '1. "I offer a jacket from adidas"
2. "I offer clothing from adidas, a jacket"
3. "By my adidas jacket"
4. "adidas jacket"
5. "jacket adidas"
6. "I offer some shoes from adidas"
7. "Selling some nice adidas shoes"
8. "I have some shoes from adidas"';
preg_match_all($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