The term YEARS AND YEARS can be expressed in a variety of ways, including EONS (4 letters), EON (3 letters), AGES (4 letters), EPOCH (5 letters), AEONS (5 letters), YONKS (5 letters), and DECADES (7 letters). EONS are the longest unit of geological time, while EON is a synonym for an indefinite and very long period of time. AGES refer to a long period of time, usually associated with a particular event or era. An EPOCH is a period of time marked by significant events or changes, while an aeon is an indefinitely long period of time. Yonks is a British slang term for a long time, and DECADES are periods of 10 years.