Synonyms of "renege" offer different ways to express the act of going back on a promise or commitment.
"go back on" is a common synonym. It implies retracting or not following through on something one has previously agreed to. For example, "He went back on his word to help with the project."
"break a promise" is a straightforward expression that clearly indicates not fulfilling a pledge. "She broke a promise to meet him for lunch."
"default on" is often used in more formal or financial contexts. It means failing to meet an obligation. "The company defaulted on its loan payments."
"repudiate" is a stronger word that suggests a deliberate rejection or disowning of a promise. "He repudiated his earlier statement."
These synonyms of "renege" all convey the sense of not living up to an agreement or commitment in different degrees and contexts.