Ammonoid

adj, noun

adj, noun ·Rare ·Advanced level

Definitions

Noun
  1. 1
    An extinct cephalopod of the subclass †Ammonoidea (including ammonites).

    "Although the extinct externally shelled cephalopods ammonoids have an extensive fossil record, their soft tissues are very poorly known and, like extinct and living nautiloids, they are largely presumed to not have possessed an ink sac."

  2. 2
    one of the coiled chambered fossil shells of extinct mollusks wordnet
Adjective
  1. 1
    Characteristic of an ammonite.

    "Literally tens of pence with an ammonoid fossil to highlight how bling bling the world of palaeontology has become"

Example

More examples

"Although the extinct externally shelled cephalopods ammonoids have an extensive fossil record, their soft tissues are very poorly known and, like extinct and living nautiloids, they are largely presumed to not have possessed an ink sac."

Etymology

From the scientific name Ammonoidea, equivalent to Ammon + -oid.

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.