The antonyms for the word "rendering invalid" are words that imply the opposite of invalidation. Such antonyms include "validating," "acknowledging," "confirming," "approving," and "ratifying." While rendering invalid means to make something unacceptable or not legitimate, validating means to confirm or affirm its authenticity. Acknowledging means to recognize, acknowledge, or accept something. Confirming means to bear witness, agree with, or concur. Approving means to express one's acceptance or appreciation, while ratifying means to make something officially valid or binding. These antonyms can come in handy when describing situations where something is legally or morally acceptable.