nautilus

noun

nau·​ti·​lus ˈnȯ-tə-ləs 

ˈnä-

plural nautiluses or nautili ˈnȯ-tə-ˌlī 

-ˌlē,

ˈnä-

1

: any of a genus (Nautilus) of cephalopod mollusks of the South Pacific and Indian oceans with a spiral chambered shell that is pearly on the inside

called also chambered nautilus

2

: paper nautilus

Illustration of nautilus

• nautilus 1

Examples of nautilus in a Sentence

Recent Examples on the Web

But later research showed that decay processes can give a similar appearance in the eyes of cephalopods, like squid or nautiluses. —Cody Cottier, Discover Magazine, 8 July 2025

Lastly, researchers noted that the nautilus, a mollusk that also diverged from the octopus around 480 million years ago, also had a similar chromosome. —Monica Cull, Discover Magazine, 3 Feb. 2025

The nautilus draws fluid in and out of those chambers to sink or float in the water column. —Amanda Kooser, Forbes, 6 Dec. 2024

The hard shell of the nautilus encloses a series of chambers. —Amanda Kooser, Forbes, 6 Dec. 2024

Word History

Etymology

New Latin, from Latin, paper nautilus, from Greek nautilos, literally, sailor, from naus ship

First Known Use

1601, in the meaning defined at sense 1

Phrases Containing nautilus

• chambered nautilus
• paper nautilus
• pearly nautilus

Kids Definition

nautilus

noun

nau·​ti·​lus ˈnȯt-ᵊl-əs 

ˈnät-

plural nautiluses or nautili -ᵊl-ˌī 

-ˌē

1

: any of a genus of mollusks of the South Pacific and Indian oceans that are cephalopods and have a spiral chambered shell that is pearly on the inside

called also chambered nautilus

2

: paper nautilus