[ee-uh-seen] 
Geology| 1. | noting or pertaining to an epoch of the Tertiary Period, occurring from 55 to 40 million years ago and characterized by the advent of the modern mammalian orders. |
| 2. | the Eocene Epoch or Series. |
| E·o·cene (ē'ə-sēn') adj. Of or belonging to the geologic time, rock series, or sedimentary deposits of the second epoch of the Tertiary Period, characterized by warm climates and the rise of most modern mammalian families. See Table at geologic time. n. The Eocene Epoch or its system of deposits. |
əˌsin
