<p><strong>Noun</strong></p><ul><li>one of a series of rows or ranks rising one behind or above another, as of seats in an amphitheater, boxes in a theater, guns in a man-of-war, or oars in an ancient galley.</li><li>one of a number of galleries, as in a theater.</li><li>a layer; level; stratum: The wedding cake had six tiers.</li><li>All three tiers of the firm's management now report to one director.</li><li>Australian. a mountain range.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>to arrange in tiers.</li></ul><p><strong>Verb (used without object)</strong></p><ul><li>to rise in tiers.</li></ul>