Related Clues:

• Has another birthday
• They're a part of every century
• Vast expanse of time
• Boundless time
• Subjects of white lies, sometimes
• See 66-Across
• Fortnight's 14
• Lotsa time
• Geologic time unit
• Gets mellower
• What seems like forever
• Iron and Bronze, for two
• Piles on birthdays
• A very long period of time
• 365 billion days, in astronomy