| Vast span | 9 |
| Unimaginably long time | 22 |
| Unfathomably long time | 22 |
| Uncountable years | 17 |
| Umpteen millennia | 17 |
| Two or more eras | 16 |
| String of periods | 17 |
| Span of time | 12 |
| Several eras | 12 |
| Series of periods | 17 |
| Seemingly endless time | 22 |
| Reeeeeeally long time | 21 |
| Reeeeeally long time | 20 |
| Proterozoic, for one | 20 |
| Phanerozoic, for instance | 25 |
| Period too long to measure | 26 |
| Period in the earth's history | 33 |
| Millions of lifetimes | 21 |
| Many lifetimes | 14 |
| Longish time span | 17 |
| Longish span | 12 |
| Longest division of time, in geology | 36 |
| Long, long, long time period | 28 |
| Long geological span | 20 |
| Lengthy interval | 16 |
| L-o-n-g time period | 19 |
| It's split into eras | 24 |
| It's comprised of ages and ages | 35 |
| It takes forever | 16 |
| It may seem like an eternity | 28 |
| Indefinable time | 16 |
| Heck of a long time | 19 |
| Geology term | 12 |
| Geology period | 14 |
| Forever and a day, seemingly | 28 |
| Extremely long time period | 26 |
| Extensive period | 16 |
| Exceedingly long time | 21 |
| Era upon era | 12 |
| Clock watcher's wait, seemingly | 35 |
| Billion-year time period | 24 |
| Billion-year span | 17 |
| Basically forever | 17 |
| Astronomically long time | 24 |
| A looooong time | 15 |
| A lo-o-ong time | 15 |
| A gazillion years, seemingly | 28 |
| A billion years, in geology | 27 |
| 365 billion days, geologically | 30 |
| 365 billion days, astronomically | 32 |
| 1,000,000,000 years, in geology | 31 |
| ___ Productions ("Skyfall" company) | 45 |
| What a waiting time may seem | 28 |
| What a houseguest's stay might feel like | 44 |
| Waiting time at the motor vehicle bureau, seemingly | 51 |
| Wait time at the cashiers on Black Friday, seemingly | 52 |
| Wait for a bus on a rainy day? | 30 |
| Wait at the motor vehicle bureau, say | 37 |
| Very, very long time | 20 |
| Very long time period | 21 |
| Very long Supergrass song? | 26 |
| Very long interval | 18 |
| Vast timeframe | 14 |
| Vast time frame | 15 |
| Vast stretch | 12 |
| Vast age | 8 |
| Unnumbered years | 16 |
| Unit in astronomy | 17 |
| Unimaginable time period | 24 |
| Unbelievably long time | 22 |
| Two or more geological eras | 27 |
| Two or more eras, in geology | 28 |
| Two or more eras, in geologic time | 34 |
| Twenty bajillion years | 22 |
| Timepiece? | 10 |
| Time spent calling call centers, seemingly | 42 |
| Time on hold, seemingly | 23 |
| Time measured in ages | 21 |
| Time it takes to get to a human being when calling a call center, seemingly | 75 |
| Time it seemingly takes to get a tax refund | 43 |
| Time in a waiting room, seemingly | 33 |
| Time between ice ages | 21 |
| Time between checks, for a freelancer, seemingly | 48 |
| Thousands of generations | 24 |
| This is going to take a while | 29 |
| The time of many billions of lives | 34 |
| The longest time? | 17 |
| Ten megacenturies | 17 |
| Super-long time | 15 |
| Super-freaking-long time | 24 |
| Span longer than an era | 23 |
| Relative of a saeculum | 22 |
| Really long geological time | 27 |
| Reallllly long time | 19 |
| Quite a span | 12 |
| Quasi-opposite of "flash" | 35 |
| Proterozoic or Archeozoic, e.g. | 31 |
| Proterozoic ___ | 15 |
| Progeny of Eternity and Infinity, in Marvel Comics | 50 |
| Phanerozoic, e.g. | 17 |