If your $arr variable is sanitized and safe to build a query with, you can use union operators to build a table containing all the words in the array, then you can left join that table to table.field and only keep array items where there was no match.
$arr = array('one','two');
$sql = "select item from (
select '" . implode("' item union select '",$arr). "' item
) t1 left join table t2 on t2.field = t1.item
where t2.field is null";
this will produce the following sql
select item from (select 'one' item union select 'two' item) t1
left join table t2 on t2.field = t1.item
where t2.field is null