Eocambrian is a loosely used, imprecisely defined term referring to the latest (youngest) portion of time in the Precambrian Eon or to the uppermost Precambrian sediments which were continuously deposited across the Precambrian-Cambrian time boundary.
While the term had some usage in older literature, it does not appear on the official ICS time scale nor in the AGI Glossary of Geology.
References
Eocambrian Wikipedia(Text) CC BY-SA