Term id – NOT IN
$tax_query = array( array( 'taxonomy' => 'allergeni', 'terms' => '25', 'field' => 'term_id', 'operator' => 'NOT IN', ), );
$tax_query = array( array( 'taxonomy' => 'allergeni', 'terms' => '25', 'field' => 'term_id', 'operator' => 'NOT IN', ), );