CBA Stands for collective bargaining agent. Trade unions and collective bargaining agents are differentiated by the results of a majority vote by union workers. To become the collective bargaining agent for a group of union workers, the trade union must be elected by those workers to be their representative in negotiating the terms of their pay, benefits and other working conditions, such as health and safety provisions, and retirement or pension contributions. That said, all collective bargaining agents may be trade unions, but all trade unions may not be collective bargaining agents