Antonyms of adj pessimistic

1 sense of pessimistic

Sense 1
pessimistic (vs. optimistic) -- (expecting the worst possible outcome)

optimistic (vs. pessimistic) -- (expecting the best in this best of all possible worlds; "in an optimistic mood"; "optimistic plans"; "took an optimistic view")
        => bullish -- (expecting a rise in prices)
        => cheerful, pollyannaish, upbeat -- (pleasantly (even unrealistically) optimistic)
        => rose-colored, rosy -- (reflecting optimism; "a rosy future"; "looked at the world through rose-colored glasses")
        => starry-eyed -- (unrealistically or naively optimistic; "a starry-eyed reformer"; "starry-eyed idealism")
        => sanguine -- (confidently optimistic and cheerful)

Similarity of adj pessimistic

1 sense of pessimistic

Sense 1
pessimistic (vs. optimistic) -- (expecting the worst possible outcome)
       => bearish -- (expecting prices to fall)
       => demoralized, demoralised, discouraged, disheartened -- (made less hopeful or enthusiastic; "desperate demoralized people looking for work"; "felt discouraged by the magnitude of the problem"; "the disheartened instructor tried vainly to arouse their interest")
          Also See-> hopeless#1; negative#1