Worst

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Old English wierresta, wyrresta (adjective), wierst, wyrst (adverb), of Germanic origin; related to worse.

wiktionary

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From Middle English worste, wurste, warste, werste, wirste, from Old English wierrest, from Proto-Germanic *wirsistaz, superlative form of *ubilaz(“bad, evil”). Cognate with Old Saxon wirsista, wirrista(“worst”), Old High German wirst, wirsesto, wirsisto(“worst”), Danish værst(“worst”), Swedish värst(“worst”), Icelandic verstur(“worst”).

etymonline

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worst (adj.)

Old English wyrresta, from Proto-Germanic *wers-ista- (source also of 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.)

"damage, inflict loss upon," c. 1600, from worst (adj.). Meaning "defeat in argument" is from 1650s. Related: Worsted; worsting.