<p><strong>Adverb:</strong></p><ul><li>One following or behind the other: to drive horses tandem.</li></ul><p><strong>Adjective:</strong></p><ul><li>Having animals, seats, parts, etc., arranged tandem or one behind another.</li></ul><p><strong>Noun:</strong></p><ul><li>A vehicle, as a truck, tractor, or trailer, in which a pair or pairs of axles are arranged in tandem.</li><li>Tandem bicycle.</li><li>Tandem trailer (def 1).</li><li>A team of horses harnessed one behind the other.</li><li>A two-wheeled carriage with a high driver's seat, drawn by two or more horses so harnessed.</li><li>Any of various mechanisms having a tandem arrangement.</li></ul>