1. (n.) A disposition to take the most hopeful view; -- opposed to pessimism\.

2. (n.) The opinion or doctrine that everything in nature, being the work of God, is ordered for the best, or that the ordering of things in the universe is such as to produce the highest good.

Leibnizian optimism Pollyannaism blitheness blithesomeness bright outlook bright side brightness buoyancy cheer cheerful expectation cheerfulness cheeriness cheery vein eupeptic mien geniality gladness gladsomeness good cheer happiness hope hopefulness idealism millennialism optimisticalness perfectibilism perfectionism philosophical optimism pleasantness positivism radiance rosy expectation rosy outlook sanguine expectation sanguine humor sanguineness sanguinity silver lining sunniness utopianism winsomeness