Division of geological time (3)
'division of geological time' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for era that I've seen before include "Significant time" , "Long historic period" , "Series of years" , "Important date" , "Aeon" .)
'division of geological time' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for aeon that I've seen before include "Eternity" , "Indefinitely long period of time" , "Immeasurably long period of time" , "With lots of time" , "Vast time period" .)
(Other definitions for epoch that I've seen before include "Point in time fixed by some great event" , "extended period" , "years" , "Aeon" , "remarkable time" .)