The term "over-board" refers to something that has gone beyond acceptable limits or has been taken too far. An antonym for this word would be "under-board," which means something that falls short of expectations or is inadequate. Another possible antonym would be "within limits," indicating compliance with established guidelines or regulations. Alternatively, the opposite of "over-board" could be expressed as "restrained," meaning to exercise caution and avoid going too far. Overall, antonyms for the term "over-board" suggest a sense of balance, responsibility, and appropriateness that is lacking in the original word.