| Answer | Crossword Clue |
|---|---|
| MILLENNIA | 1000-year periods |
| QUINQUENNIA | Five-year periods. |
| EONS | Billion-year periods |
| YULETIDES | Year-end periods |
| LUSTRA | Five-year periods |
| DECADES | 10-year periods |
| CENTURIES | Hundred-year periods |
| PENTADS | Five-year periods |
| BIENNIA | Two-year periods |
| PENTADS | Five-year periods. |
| CENS | 100-year periods: Abbr. |
| TRIMESTERS | Periods of the academic year |
| TERMS | Six-year periods for senators and two-year periods for representatives |
