“A public declaration of advocated opinion, intent, viewpoint, etc., especially a political exhortation or proclamation of aesthetic principles; avowal; credo. Plural: manifestos, manifestoes.
‘How often he had seen her, as they sat together in the evening lamplight, with a pad of it propped on her knee as she drafted a letter to her Congressman, or flaming manifesto for one or another of the ecological causes into which she threw herself, and sometimes him.’” Peter De Vries, Madder Music
Grambs, David. The Random House Dictionary for Writers and Readers. New York: Random House, 1990.