<p><strong>Verb</strong></p><ul><li>to mark with a line or lines underneath; underline, as for emphasis.</li><li>to stress; emphasize: The recent tragedy underscores the danger of disregarding safety rules.</li></ul><p><strong>Noun</strong></p><ul><li>a line drawn beneath something written or printed.</li><li>music for a film soundtrack; background for a film or stage production.</li></ul>