The term 'play ball' is commonly used in sports to signify the beginning of a game. It can also be used as a metaphor for cooperation and collaboration. The crossword solutions for this term are COMPLY (6 letters), AGREE (5 letters), ACQUIESCE (9 letters), COOPERATE (9 letters), and COOERATE (8 letters). These words all mean to accept or COMPLY with a request, to AGREE to something, or to COOPERATE with someone. They all suggest that two or more parties are working together in order to achieve a common goal.