| Big time for crosswords? | 24 |
| Big hunk of time | 16 |
| Awfully long stretch | 20 |
| Awfully long span | 17 |
| At least two eras | 17 |
| Astronomical time span | 22 |
| Astronomical stretch | 20 |
| Annoying wait, facetiously | 26 |
| An extremely long period of time | 32 |
| Amazingly long time | 19 |
| About a billion years | 21 |
| About 525 trillion minutes, in astronomy | 40 |
| A thousand ages | 15 |
| A long period of time | 21 |
| A long long time | 16 |
| A frickin' long time | 24 |
| A billion years, to Hubble | 26 |
| A billion years, to geologists | 30 |
| 365 billion days, in astronomy | 30 |
| 10 megacenturies | 16 |
| Important times | 15 |
| Geologic periods | 16 |
| Billions of years | 17 |
| Vast stretches of time | 22 |
| Geological periods | 18 |
| Time spans | 10 |
| Time divisions | 14 |
| Geological times | 16 |
| Geological time periods | 23 |
| Astronomical periods | 20 |
| Ages on end | 11 |
| Zillions of years | 17 |
| Long times to wait | 18 |
| From here to eternity | 21 |
| Billions of years, geologically | 31 |
| A seeming eternity | 18 |
| Long, long times | 16 |
| Geologic divisions | 18 |
| Thousands of years | 18 |
| They last a long time | 21 |
| Incalculable amount of time | 27 |
| Geologic time periods | 21 |
| Extremely long time frames | 26 |
| Stretches of history | 20 |
| Spans of history | 16 |
| Practically forever | 19 |
| Hundreds of centuries | 21 |
| Geologic time spans | 19 |
| Geologic time divisions | 23 |
| Centuries of centuries | 22 |
| Ages upon ages of time | 22 |
| Very long stretches | 19 |
| Units on the geologic time scale | 32 |
| Units of time | 13 |
| Units of geologic time | 22 |
| Thousands of centuries | 22 |
| They seem to last forever | 25 |
| Millennia on end | 16 |
| Mammoth time units | 18 |
| Major time periods | 18 |
| Long, long periods | 18 |
| Lengthy time units | 18 |
| Immeasurably long periods of time | 33 |
| Immeasurable periods | 20 |
| Geologists' times | 21 |
| Geological divisions | 20 |
| Geologic timespans | 18 |
| Geologic times | 14 |
| Extremely long stretches | 24 |
| Evolutionary time periods | 25 |
| Eternities, seemingly | 21 |
| Donkey's years | 18 |
| Cosmic cycles | 13 |
| Billions and billions of years | 30 |
| Billion-year increments | 23 |
| An eternity, seemingly | 22 |
| A long, long, long time | 23 |
| A kazillion years, it seems | 27 |
| A billion years, geologically | 29 |
| Years without end | 17 |
| Very long times | 15 |
| Very long spell | 15 |
| Very long spans | 15 |
| Very long periods of time | 25 |
| Very long periods | 17 |
| Vast sweep of time | 18 |
| Vast periods | 12 |
| Unimaginably long stretches | 27 |
| Unfathomable stretches | 22 |
| Tremendous spans | 16 |
| Times immeasurable | 18 |
| Time, seemingly, between finishing a freelance job and getting paid | 67 |
| Time upon time | 14 |
| Time to evolve? | 15 |
| Time beyond measure | 19 |
| Time and time again | 19 |
| Thousands and thousands of years | 32 |
| Stellar periods | 15 |
| Some collars and jackets | 24 |
| Segments of eternity | 20 |