Even so is a phrase that is used to introduce an idea or statement that may be contrary to what has been said previously. In other words, it is a phrase that is used to show balance or contrast in a sentence. Some possible synonyms for "even so" are "nevertheless," "however," "still," "yet," "notwithstanding," "regardless," "despite," "although," "though," "but," and "in spite of." All of these words are used to show that something unexpected or contradictory is about to be said, but they all have slightly different connotations that can alter the meaning of the sentence.