The term "most on-the-spot" refers to quick and efficient decision-making capabilities. The opposite of this trait would be indecisiveness or a lack of adaptability. Antonyms for "most on-the-spot" could include inflexible, unprepared, hesitant, uncertain, unresponsive, and unprepared. If someone is not quick to make decisions, they might be considered slow, calculating, cautious or deliberate, which are also antonyms to being on-the-spot. Therefore, it is essential to be aware of the opposite of the term as it helps you better identify which trait you are lacking in and work to improve it.