<p><strong>Noun</strong></p><ul><li>plural nau·ti·lus·es, nau·ti·li [nawt, -l-ahy, not, -]</li><li>Also called chambered nautilus, pearly nautilus.</li><li>any cephalopod of the genus Nautilus, having a spiral, chambered shell with pearly septa.</li><li>paper nautilus.</li><li>(initial capital letter) the first nuclear-powered submarine launched by the U.S. Navy.</li></ul>