/pes"euh miz'euhm/ , n.
1. the tendency to see, anticipate, or emphasize only bad or undesirable outcomes, results, conditions, problems, etc.: His pessimism about the future of our country depresses me.
2. the doctrine that the existing world is the worst of all possible worlds, or that all things naturally tend to evil.
3. the belief that the evil and pain in the world are not compensated for by goodness and happiness.
[ 1785-95; pessim ( us ), suppletive superl. of malus bad + -ISM; modeled on optimism ]