The phrase "goes even-steven" is an idiom that means everything is balanced or fair. Some antonyms, or opposite words, for this phrase could be "lopsided," "uneven," "unfair," or "imbalanced." These words suggest that something is not equal or proportional, and there may be an advantage or disadvantage to one side over the other. In contrast, synonyms, or words that have a similar meaning, for "even-steven" could include "fair," "just," "equitable," or "equal." These words indicate that everything is balanced or even, with neither side having an advantage over the other.