Upanāha
Upanāha is a Buddhist term translated as "resentment" or "enmity". It is defined as clinging to an intention to cause harm, and withholding forgiveness. It is one of the twenty subsidiary unwholesome mental factors within the Mahayana Abhidharma teachings.
The Abhidharma-samuccaya states:
Alan Wallace described upanāha as "a lingering holding of anger ".