Alternative form of オルドビス紀 (Orudobisu-ki, “Ordovician”)

geology

geological features

one thing

age, era, period (of time) / the times, spirit of the age / antiquity / a time in one's life, one's days (in college etc.)

scholarship; learning; knowledge

as far as ... is concerned; in terms of ...

a target, a mark, a bullseye / an objective, an object (of doing something)

a surname

rule; regulation / age; era; period / to record; to write down