/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. [href="module.php?name=Lexikon&file=search&eid=1&query=Jargon File">Jargon File] (1995-02-01)