Contains and not contains are good but we need also IS and ISNOT to get exact matches.
It's slightly complicated, but you can stack the
:not, :contains, and :has selectors to get exactly the match you need. e.g.
will match any para that contains 'DOG' except if those that contains 'DOGGED'.
But if there is multiple DOG*? I want only DOG, not DOGGED, DOGGY, DOGEMON?