viscerally

The word's journey begins with the Latin viscus, meaning an internal organ or flesh, which itself is of uncertain, possibly Proto-Indo-European, origin. The plural form viscera entered English to denote the internal organs of the body, particularly the heart, liver, and intestines, which were historically associated with powerful emotions. The addition of the adjectival suffix '-al' created 'visceral,' describing things pertaining to these organs or, by metaphorical extension, to deep, instinctive feelings as opposed to reasoned thought. Finally, the adverbial suffix '-ly' was appended, forming 'viscerally' to describe an action or reaction performed in such an instinctive, gut-level manner.