<p><strong>Verb (used with object)</strong></p><ul><li>to make more trim or spruce; improve in appearance (usually followed by up): Try to smarten up your outfit.</li><li>to make brisker, as a pace.</li><li>to sharpen the judgment or broaden the experience of; educate (usually followed by up): Someone has to smarten him up about dealing with people.</li></ul><p><strong>Verb phrase</strong></p><ul><li>to groom oneself: to smarten up before dinner.</li><li>to become aware of one's mistakes, shortcomings, etc., and make efforts to correct them: If you don't smarten up, you're going to be out of a job.</li></ul>