The best replacement for optimism is pessimism.

The best alternatives to optimism are rated as following:
★★★★★  pessimism
★★★  hope
★★★  realism
★  denial
★  pessimistic
  conservatism
  positive thinking
  skepticism
  confidence
  voltaire's candide
  pessimism optimists

Your alternative for optimism is not listed? Suggest!
Speaking about optimism, one probably shouldn't forget about realism.

Other search terms related to optimism and their ratings are:
★★★★★ realism
You have in mind a companion for optimism and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of optimism in all years. Click on graph for more.
optimism
pessimism
hope