worst (adj.) Look up worst at Dictionary.com
Old English wyrresta, from Proto-Germanic *wers-ista- (cognates: Old Saxon wirsista, Old Norse verstr, Old Frisian wersta, Old High German wirsisto), superlative of PIE *wers- (1) "to confuse, mix up" (see war (n.)). Phrase in the worst way (1839) is from American English sense of "most severely." The adverb is Old English wyrst; the noun, "that which is most evil or bad," is from late 14c.
worst (v.) Look up worst at Dictionary.com
"damage, inflict loss upon," c.1600, from worst (adj.). Meaning "defeat in argument" is from 1650s. Related: Worsted; worsting.