An Etymological Dictionary of the German Language/Annotated/kochen
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kochen, ‘to cook,’ from the equivalent Middle High German kochen, Old High German chohhôn, from Latin coquere (more accurately *coquâre?). The High German word could not remain a strong verb, because the vowel of the stem differed from the analogy of verbs of that class. In Romance note French cuire, Italian cuocere. Compare also Kuchen.