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

Ammonites used the chambers in their shells to control buoyancy, much like the modern nautilus. — Torben Rick, The Conversation, 18 June 2026

The creature, Clements and his team determined, is actually a relative of the nautilus — a cephalopod with both tentacles and a shell. — Samantha Agate, Miami Herald, 23 Apr. 2026

New research has reclassified the specimen as a relative of the nautilus, a cephalopod with both tentacles and a shell. — Samantha Agate, Fort Worth Star-Telegram, 23 Apr. 2026

The fossil was identified as the world's oldest octopus in 2000 — but is now considered the oldest soft-tissue nautilus in the world. — Andrea Margolis, FOXNews.com, 13 Apr. 2026

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