RhymeZone: mesoproterozoic definitions

Definitions of Mesoproterozoic:

adjective: (geology) Of a geologic era within the Proterozoic eon; comprises the Calymmian, Ectasian and Stennian periods from about 1600 to 900 million years ago, when the Rodinia supercontinent was formed.
noun: (geology) The Mesoproterozoic era.

(Definitions from Wiktionary)