| Answer | Crossword Clue |
|---|---|
| ERA | Period of years. |
| CENTURY | Period of years. |
| ERA | Period of years |
| CEN | Period of years: abbr. |
| TEENS | Transition period of years. |
| CEN | Period of years: Abbr. |
| LUSTRUM | Period of five years. |
| EON | Period of many years |
| CHILIAD | Period of a thousand years. |
| DECADE | A certain period of years. |
| OCTAETERIC | Relating to a period of eight years. |
| TRICENTENARY | Relating to a period of 300 years |
| IRONAGE | Period of human history that began about 3,000 years ago |
| CAMBRIAN | Time period, 500 million years ago. |
| AGES | Middle ... (period from 500 to 1500 years ago) |
