<p><strong>Noun</strong></p><ul><li>one of four copies or identical items, especially copies of typewritten material.</li><li>a fourth item or copy of something.</li></ul><p><strong>Adjective</strong></p><ul><li>consisting of four identical parts.</li><li>pertaining to a fourth item or copy of something.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>quad·ru·pli·cat·ed, quad·ru·pli·cat·ing.</li><li>to produce or copy in quadruplicate.</li><li>to make four times as great.</li></ul>