Coupé is a classical ballet term meaning “cut” or “cutting.” A coupé describes a step where one foot cuts the other foot away, taking its place. Its usually done as an in-between step for a larger step, such as a coupé jeté or a coupé-chassé en tournant (the typical preparation for many big jumps for males).
If a coupé is not done as part of a preparation step, it is usually done in succession, though even this isn’t very common outside of class.