The phrase "make book" generally means to place a bet, especially in horse racing. There are a number of antonyms that can be used to describe the opposite of making a bet or taking a wager. One possible antonym is "abstain," which means to refrain from taking part in an activity or abstaining from a certain behavior. Another possible antonym is "doubt," which refers to a lack of confidence or belief in the outcome of an event. Other antonyms could include "ignore," "overlook," or "disregard," all of which suggest a lack of interest or involvement in the betting process.