nautiloid

American  

[nawt-l-oid] / ˈnɔt lˌɔɪd /

noun

1. a mollusk of the subclass Nautiloidea, including nautiluses and many fossil species that were abundant in the Ordovician and Silurian periods.

---

adjective

1. noting or pertaining to a nautiloid.

nautiloid British  

/ ˈnɔːtɪˌlɔɪd /

noun

1. any mollusc of the Nautiloidea, a group of cephalopods that includes the pearly nautilus and many extinct forms

---

adjective

1. of, relating to, or belonging to the Nautiloidea

nautiloid Scientific  

/ nôt′l-oid′ /

1. Any of various cephalopod mollusks of the subclass Nautiloidea, having a straight or coiled shell divided internally into a series of chambers of increasing size connected by a central tube. The nautiloids include the modern nautiluses as well as numerous extinct species dating back as far as the Cambrian Period.

---

Etymology

Origin of nautiloid

First recorded in 1720–30; nautil(us) ( def. ) + -oid ( def. )

Example Sentences

The teeth revealed matched those of a fossil nautiloid that was found at the same site.

From BBC • Apr. 8, 2026

The Paleocadmus specimens from the Mazon Creek site in Illinois now represent the oldest known example of nautiloid soft tissue in the fossil record, surpassing the previous record by about 220 million years.

From Science Daily • Apr. 7, 2026

The teeth closely matched those of a known fossil nautiloid species, Paleocadmus pohli, which has been found at the same site.

From Science Daily • Apr. 7, 2026

We now have the oldest soft tissue evidence of a nautiloid ever found, and a much clearer picture of when octopuses actually first appeared on Earth.

From Science Daily • Apr. 7, 2026

Shell nautiloid, with simple sutures, siphuncle dorsal, that is, internal.

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 6 "Celtes, Konrad" to "Ceramics" by Various