The term 'Flight Unit' can be broken down into three separate words: STAIR (5 letters), STEP (4 letters), and STAIRSTEP (9 letters). STAIR is a set of steps leading from one level to another, usually inside a building. STEP is a single movement of the foot in walking or running. STAIRSTEP is a combination of stairs and steps, which is often used to describe a gradual increase or decrease in something. Together, these three words form the term 'Flight Unit', which is used to describe a unit of measurement for the speed of an aircraft.