RhymeZone: neoproterozoic definitions

Definitions of Neoproterozoic:

adjective: (geology) Of a geologic era within the Proterozoic eon; comprises the Tonian, Cryogenian and Ediacaran periods from about 1000 to 544 million years ago, when algae and sponges flourished.
noun: (geology) The Neoproterozoic era.

(Definitions from Wiktionary)