Detest

google

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late 15th century: from Latin detestari, from de- ‘down’ + testari ‘witness, call upon to witness’ (from testis ‘a witness’).

wiktionary

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From Middle French detester, from Latin detestari(“to imprecate evil while calling the gods to witness", "denounce", "hate intensely”), from de- + testari(“to testify, bear witness”), from testis(“a witness”); see test, testify.

etymonline

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detest (v.)

1530s, "execrate, hate, dislike intensely," also "to curse, to call God to witness and abhor," from French détester, from Latin detestari "to curse, execrate, abominate, express abhorrence for," literally "denounce with one's testimony," from de "from, down" (see de-) + testari "be a witness," from testis "witness" (see testament). Related: Detested; detesting.