$re = '/\bo{1,2}[\sh]?b\s?i{1,2}\b/';
$str = 'obi
obi baumarkt
baumarkt obi
obi-baumarkt
baumarkt-obi
obiwan
tobi
grobian';
preg_match_all($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