The term RESPONSE TO AN ORDER can be summarized by two crossword solutions: AYE (3 letters) and YESSIR (6 letters). AYE is a response to an order that is used to show agreement or acceptance. It is derived from the Middle English word 'ayein, ' which means 'EVER' or 'ALWAYS.' YESSIR is another response to an order, usually used to show respect or deference. It is derived from the Middle English phrase 'yea, sir, ' which was used to address a superior.