전혀 아니에요.

The word '전혀' (jeonhyeo) is derived from the Sino-Korean word 全 (jeon, meaning 'whole, entire') and 然 (hyeo, a suffix that makes an adjective or noun into an adverb, often implying 'like that' or 'such'). Over time, its usage became specifically tied to emphasizing a complete negation when combined with negative verbs or adjectives. '아니에요' (anieyo) is the polite declarative form of the verb '아니다' (anida), which means 'to not be' or 'to be not.' The root '아니-' (ani-) is a very old Korean negative existential verb, and '-에요' (-eyo) is a common polite ending for verbs and adjectives. Therefore, '전혀 아니에요' literally translates to 'it is entirely not so' or 'absolutely not.' Its strong and unequivocal nature comes from the combination of the emphatic adverb '전혀' and the direct negation '아니에요'.