To occur in a successive manner: day alternating with night. To act or proceed by turns: The students alternated at the computer. To pass back and forth from one state, action, or place to another: alternated between happiness and depression. Electricity To reverse direction at regular intervals in a circuit. To do or execute by turns. To cause to alternate: alternated light and dark squares to form a pattern. Happening or following in turns; succeeding each other continuously: alternate seasons of the year. Designating or relating to every other one of a series: alternate lines. Serving or used in place of another; substitute: an alternate plan. See Usage Note at alternative. Botany Arranged singly at each node, as leaves or buds on different sides of a stem. Arranged regularly between other parts, as stamens between petals. A person acting in the place of another; a substitute. An alternative.