<p><strong>Verb</strong></p><ul><li><p>(used without object):</p><ul><li>to interchange repeatedly and regularly with one another in time or place; rotate (usually followed by with): Day alternates with night.</li><li>to change back and forth between conditions, states, actions, etc.: He alternates between hope and despair.</li><li>to take turns: My sister and I alternated in doing the dishes.</li><li>Electricity: to reverse direction or sign periodically.</li><li>Linguistics: to occur as a variant in alternation with another form.</li></ul></li><li><p>(used with object):</p><ul><li>to perform or do in succession or one after another: to alternate comedy acts; to alternate jogging and walking.</li><li>to interchange successively or regularly: to alternate hot and cold compresses.</li></ul></li></ul><p><strong>Adjective</strong></p><ul><li>being in a constant state of succession or rotation; interchanged repeatedly one for another: Winter and summer are alternate seasons.</li><li>reciprocal; mutual: alternate acts of kindness.</li><li>every second one of a series: Read only the alternate lines.</li><li>constituting an alternative: The alternate route is more scenic.</li><li>Botany: placed singly at different heights on the axis, on each side in succession, or at definite angular distances from one another, as leaves.</li><li>opposite to the intervals between other organs: petals alternate with sepals.</li></ul><p><strong>Noun</strong></p><ul><li>a person authorized to fill the position, exercise the duties, etc., of another who is temporarily absent; substitute.</li><li>Theater: either of two actors who take turns playing the same role; an understudy.</li></ul>