The term 'ATHLETIC UNIT' can be broken down into two crossword solutions: INNING (6 letters) and TEAM (4 letters). An inning is a unit of play in baseball, softball, and other sports. It is the period of time between when the first batter steps up to the plate and when the third out is made. A TEAM is a group of people who work together to achieve a common goal. In sports, teams are typically composed of players who compete against other teams.