period vs Ordovician period

period and Ordovician period both are nouns.

Word	Noun	Adjective	Verb	Adverb
period	Yes	No	No	No
Ordovician period	Yes	No	No	No

period (noun)	Ordovician period (noun)
a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations	the period from 500 million to 425 million years ago; characterized by conodonts and ostracods and algae and seaweeds
the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause
an amount of time
the interval taken to complete one cycle of a regularly repeating phenomenon
a unit of geological time during which a system of rocks formed
the end or completion of something
(ice hockey) one of three divisions into which play is divided in hockey games