pollyanna [ˌpɒliˈænə] n.
1.) A person regarded as being foolishly or blindly optimistic (American Heritage Dictionary of the English Language).
Etymology: After the heroine of the novel Pollyanna, by the American writer Eleanor Hodgman Porter (1868-1920).
"Job's crops are destroyed, his barns burned, his children taken sick, and he himself breaks out all over with boils. In this condition he is visited by a group of three friendsprofessional moralists and Pollyannasand between them and him the dramatic debate ensues" (The Man and the Book Nobody Knows, Bruce Barton, 1959).