Quitting a union is the act of formally withdrawing from membership in a labor union. It is also known as 'seceding' from the union, which is the term used in the crossword solution. Seceding from a union involves submitting a written notice to the union and ceasing to pay dues or other fees. This action can be taken for a variety of reasons, including dissatisfaction with the union's leadership or policies, or a desire to pursue other employment opportunities.