The antonyms for the word "out rivaling" are words that indicate inferiority, such as underperforming, falling short, or losing. These antonyms describe situations where one fails to achieve victory or surpass another in a competition or comparison. Other antonyms for out-rivaling include trailing, lagging, and coming in behind, which convey the opposite of being ahead or winning. When one is not able to out-rival their competition, they may be considered outmatched, outclassed, or outperformed, all of which are antonyms to the word out-rivaling. Ultimately, antonyms for out-rivaling can refer to various degrees of poor performance or inability to succeed.