A cephalopod mollusk of the genus Nautilus, especially N. pompilius, found in the Indian and Pacific oceans and having a spiral, pearly-lined shell with a series of air-filled chambers. Also called chambered nautilus, pearly nautilus.
The paper nautilus.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.