Reciprocal action is an exchange of actions between two parties, where each party responds to the other's action. The term can be broken down into two crossword solutions: TAT (3 letters) and INTERPLAY (9 letters). TAT stands for 'tit-for-TAT', which is a strategy in game theory where one party responds to the other's action with the same action. INTERPLAY refers to the mutual interaction between two parties, where each party's action affects the other. Together, these two terms describe the concept of reciprocal action, which is an exchange of actions between two parties that are mutually dependent on each other.