An act or movement of putting one leg in front of the other in walking or running. A flat surface, especially one in a series, on which to place one's foot when moving from one level to another. A measure or action, especially one of a series taken in order to deal with or achieve a particular thing. An interval in a scale; a tone (whole step) or semitone (half step). Step aerobics. Lift and set down one's foot or one foot after the other in order to walk somewhere or move to a new position. Set up (a mast) in its step. Denoting a relationship resulting from a remarriage.