I. ˈpālēəˌjēn, ˈpal- noun
Usage: usually capitalized
Etymology: German paläogen, from palä- pale- + -gen (from root of Greek genesthai to be born) — more at kin
: the earlier part of the Tertiary including the Paleocene, Eocene, and Oligocene
II. adjective
Usage: usually capitalized
: of or relating to the Paleogene