Definition

1. Noun:
   • A cephalopod mollusk: A marine animal of the Indian and Pacific Oceans, characterized by a spiral shell with many chambers and pearly partitions. It is a living fossil, related to squids and octopuses.
   • A submarine: (Capitalized, often as part of a proper name) A type of submarine, famously the first nuclear-powered submarine, the USS Nautilus.

Examples of Usage

• Noun (Animal):
  • The nautilus is often called a "living fossil" because it has remained relatively unchanged for millions of years.
  • We saw the beautiful, coiled shell of a nautilus in the aquarium exhibit.
• Noun (Submarine):
  • Jules Verne's fictional submarine in "20,000 Leagues Under the Sea" was named the Nautilus.
  • The nuclear-powered USS Nautilus made history by reaching the North Pole.

Advanced Usage

• "Chambered nautilus": The full common name for the animal (), emphasizing its multi-chambered shell.
  • The chambered nautilus creates new, larger chambers as it grows.

Variants and Related Words

• Nautili (n): A traditional plural form of .
• Nautiluses (n): A common modern plural form of .
• Nautiloid (n/adj): (Paleontology) Referring to or being an extinct, shelled cephalopod related to the modern nautilus.

Synonyms

• Cephalopod: The broader class of mollusks to which the nautilus belongs (e.g., squid, octopus).
• Submarine: A watercraft capable of independent operation underwater (for the mechanical sense).

Related Phrases and Terms

• Paper nautilus: A common name for , a different genus of octopus where the female secretes a thin, papery egg-case, not a true nautilus shell.
  • Despite the name, the paper nautilus is actually a type of octopus.

Noun

1. cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions
2. cephalopod mollusk of warm seas whose females have delicate papery spiral shells
3. a submarine that is propelled by nuclear power