<p><strong>Verb (used without object)</strong></p><ul><li>to speak in a low indistinct manner, almost to an unintelligible extent; mutter.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>to say or utter indistinctly, as with partly closed lips: He mumbled something about expenses.</li><li>to chew, or try to eat, with difficulty, as from loss of teeth.</li></ul><p><strong>Noun</strong></p><ul><li>a low, indistinct utterance or sound.</li></ul>