There are several synonyms for the phrase "put on the line" including risk, gamble, endanger, and hazard. These words all reflect a situation where something valuable is in danger of being lost or damaged. "Risk" and "gamble" imply that a decision is being made that may result in either a positive or negative outcome. "Endanger" and "hazard" suggest that something is at risk of harm or damage. In any case, the phrase "put on the line" conveys a certain sense of gravity and importance, indicating that a decision or action must be taken carefully and with full understanding of the potential consequences.