|Precambrian or Pre-Cambrian (priːˈkæmbrɪən)|
|1.||of, denoting, or formed in the earliest geological era, which lasted for about 4 000 000 000 years before the Cambrian period|
|2.||the Precambrian Archaeozoic See Proterozoic the Precambrian era|
|Pre-Cambrian or Pre-Cambrian|
|Precambrian (prē-kām'brē-ən, -kām'-) Pronunciation Key
The period of geologic time between Hadean Time and the Phanerozoic Eon, from about 3.8 billion to 540 million years ago. During the Precambrian Eon, which is divided into the Archean and Proterozoic, primitive forms of life first appeared on Earth. See Chart at geologic time.