Once and for all Definition 1 of 2Pro Tip 1/3Final Action Use when you describe an action that concludes something definitively. I quit the band once and for all. Pro Tip 2/3No Repetition It implies you won't repeat the action or that it won't become necessary again. She closed the shop once and for all. Pro Tip 3/3Strong Emphasis Adds strength to a statement, making it sound more decisive. This law will solve the problem once and for all.