Agitate the air is a process of stirring or mixing the air in order to create movement. This can be done for a variety of reasons, such as to increase air circulation, reduce humidity, or to help disperse odors. The term 'agitate the air' can also be used to describe the process of creating turbulence in the air, which can be used to help create lift for aircraft. The crossword solution for this term is STIR, which is a four-letter word meaning to move something with a circular motion.