noun
a person who refuses, denies, or opposes, esp. because of cynicism or pessimism. They went ahead with their ambitious plan despite the arguments of the naysayers.
adjective extremely loud and powerful. His stentorian voice was heard above the din of battle.
Note on word origin: In Greek mythology, Stentor was a herald said to have the voice of fifty men. Stentor died after losing a shouting contest to the divine herald, Hermes.