jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
[Latin-based antonym for optimal] Maximally bad. “This is a pessimal situation.” Also pessimize vt. To make as bad as possible. These words are the obvious Latin-based antonyms for optimal and optimize, but for some reason they do not appear in most English dictionaries, although ‘pessimize’ is listed in the OED.