1) Preclude – to prevent it from happening

 A muzzle preclude a dog from biting.

 2) Precarious – when something is unstable and likely to get worse

 You are in precarious financial situation

 3) Portent – a sign of future event especially unpleasant

 The storm seems like a portent of doom

 4) Ponderous – Heavy footed, dull 

 The show is loaded down with ponderous one-liners

 5) Precepts – rules and regulation often with religious 

 Moral precepts.

 6) Preen – when you preen, you give attention to how you dressed

 Will you stop yourself preening in front of mirror.

 7) Preponderance – A lot of it

 If you are prosecutor , your are looking for preponderance of evidence 

 8) Presage – something bad is going to happen

 He had strong presage, that he has strong time to live.

 9) Preternatural  –  beyond what is natural

 Autumn has arrived with preternatural speed.

 10) Prevaricate – to avoid answering the question directly in order to hide truth

 Do not prevaricate tell me the story straight.