The word 'more impugnable' refers to something that is open to doubt or criticism. However, if we're looking for its antonyms or opposite words, we can consider other terms that signify the opposite of this meaning. Such antonyms for 'more impugnable' might include terms like 'irrefutable,' 'incontrovertible,' 'indisputable,' 'untainted,' 'unblemished,' 'incriminable,' 'blameless,' 'indefensible,' or 'irreproachable.' These words signify a sense of righteousness or legitimacy, free from any doubt or stain. It's essential to know the antonyms and synonyms of words to expand your vocabulary, improve your communication skills and express your thoughts more effectively.