/pes' im-l/ (LatiN-based aNtoNym for "optimal") Maximally bad. "This is a pessimal situatioN." Also "pessimise" To make as bad as possible. These words are the obvious LatiN-based aNtoNyms for "optimal" aNd "optimise", but for some reasoN they do Not appear iN most ENglish dictioNaries, although "pessimise" is listed iN the OED. [JargoN File] (1995-02-01)