| OLIGOCENE | Relating to the third epoch of the Palaeogene geologic period (9) |
| AUTUMNAL | Relating to the third season of the year |
| GEMINIAN | Relating to the third sign of the zodiac (8) |
| EOCENE | Second epoch of the Palaeogene period in the geologic timescale (6) |
| LADIESDAY | Colloquial name given to the third day of the Royal Ascot race meeting (6,3) |
| PLEIOCENE | An epoch of the Tertiary period, beginning over 5.3 million years ago (9) |
| DEBAUCHEE | What's one to the third, rounding it up? (Base one is base) (9) |
| STANDREWS | Scottish town which is home to the third oldest university in the Englishspeaking world (2,7) |
| DEVONIAN | A geologic period in the Palaeozoic era, known as the Age of Fishes, during which the first ammonites appeared |
| SILURIAN | Geologic period between the Ordovician and Devonian periods of the Palaeozoic era (8) |
| PLIOCENE | Second epoch of the Neogene period in the Cenozoic era in the geologic timescale (8) |
| NEOGENE | First epoch of the Neogene Period of the Cenozoic Era, lasting from about 23 to 5 million years ago (7) |
| LIASSIC | Of the earliest epoch of the Jurassic period (7) |
| PLEISTOCENE | First epoch of the Quaternary period, followed by the present Holocene epoch (11) |
| MIOCENE | Fourth epoch of the Tertiary period, occurring between the Oligocene and the Pliocene (7) |
| CHARLIE | Appellation given by the Western Allies to the third crossing point opened by them on the Berlin Wall during the Cold War |
| TATLIN | Vladimir, Russian artist commissioned to design the Monument to the Third International (6) |
| NEOCENE | Geologic period within the Cenozoic era (7) |
| ICEAGE | Any geologic period during which thick ice sheets cover vast areas of land. (3,3) |
| IRONAGE | Third and last epoch of the three divisions of European prehistory (4,3) |
