period vs geological era

period and geological era both are nouns.

Word	Noun	Adjective	Verb	Adverb
period	Yes	No	No	No
geological era	Yes	No	No	No

period (noun)	geological era (noun)
a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations	a major division of geological time; an era is usually divided into two or more periods
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