'ultimate optimism' is correct and usable in written English.
You can use it to refer to a kind of hope or confidence that a favorable outcome will happen, even when it seems unlikely. For example, "Despite all the obstacles in their way, they managed to succeed thanks to their ultimate optimism."
"Pragmatism, acknowledgement of risk, but ultimate optimism.
He described it as a lyric-heroic symphony that explored the sufferings and ultimate optimism of man.
Despite his ultimate optimism, Hartmann has been considered a pessimist whose views contributed to such extreme 20th-century philosophies as nihilism.
Again, his disavowal of the cynics' reductive perspective, and his use of the "powerful myth of Christ's passion" to illustrate "the strange process whereby human beings transform naturally occurring events into actively generated symbols", conveys his ultimate optimism about the generative communal capacity of consciousness.
Eric Idle et al deliver the ultimate ode to optimism while being subjected to a mass crucifixion.
She argues that the Cercle Harmonique's recorded spirit messages reflect an "egalitarian republicanism" and racial struggle that paralleled the trajectory of optimism and ultimate failure of black social and political progress in the Civil War and Reconstruction-era South (p. 6).
Yet there is an infectious joy in being a Clippers fan and rooting for the ultimate underdog with unbridled optimism.
Amy Poehler as Leslie Knope, the deputy director of the Pawnee parks department, who has not let politics dampen her sense of optimism; her ultimate goal is to become President of the United States.
Mr. Silverstein has lost a series of crucial rulings leading up to the trial, but both sides have expressed optimism over the ultimate outcome.
Augustine is carefully orthodox, after the spirit of his and succeeding times, but adds his own emphasis in the way he teaches the resemblance between God and man: the threeness of God he finds reflected in a galaxy of similar triples in the human soul, and he sees there both food for meditation and deep reason for optimism about the ultimate human condition.
Weighed down by debt, he blames over-optimism as the ultimate culprit.
