Outrivals is a term used to describe a situation where someone or something surpasses others in a competition or comparison. The antonyms of outrivals are words that describe situations where someone or something does not outperform others or is inferior in a competition. Some antonyms for outrivals include "fails," "underperforms," "loses," "performs poorly," "underachieves," "falls short," "comes in last," "is outmatched," "comes up short," and "lacks excellence." These words are often used in situations where someone or something did not meet expectations, perform as well as anticipated, or simply did not compare favorably to others.