Odds on is a phrase that describes the likelihood of an event occurring. If something is described as being odds on, it means that it is highly likely to happen. There are many synonyms for odds on, such as probable, likely, certain, and expected. These words all suggest a high degree of certainty or probability that something will happen. Other synonyms that can be used include inevitable, in the bag, assured, and secure. No matter which synonym is used, the common theme is that there is a high likelihood of something happening. So, when something is described as being odds on, it is best to be prepared for it to occur.