php preg_replace remove entire line (from a block of many lines ) if it contains an occurence of a word

Guys ( preg_replace gurus );

I am looking for a preg_replace snippet , that i can use in a php file whereby if a word appears in a particular line, that entire line is deleted/replaced with an empty line

pseudocode:

$unwanted_lines=array("word1","word2"."word3");
$new_block_of_lines=preg_replace($unwanted_lines, block_of_lines);

Thanx.