| OSSIAN | A legendary Irish hero and bard of the 3rd century AD |
| PLOTINUS | Egyptian-born Roman philosopher of the 3rd century AD who founded Neoplatonism (8) |
| MANETHO | Egyptian priest of the 3rd century BC whose Greek Aegyptiaca (History of Egypt) originated the concept of pharaonic dynasties (7) |
| ARCHIMEDEAN | Relating to the Syracuse-born mathematician of the 3rd century BCE |
| EUCLID | Geometrician of the 3rd century BC (6) |
| PERPETUA | Christian martyr of the 3rd century; her comartyr Felicity, was her slave (8) |
| CCC | Last year of the 3rd century |
| CCL | Middle of the 3rd century |
| CCLI | Middle of the 3rd century |
| FENIAN | Legendary Irish hero |
| ELMO | Patron saint of sailors, properly known as Erasmus of Formia (3rd century AD) (4) |
| CECIL | Literary critic and Oxford don who was a grandson of the 3rd Marquess of Salisbury, the Victorian statesman who served as prime minister three times (5) |
| SASSANID | Ancient Persian empire of the 3rd to 7th century A.D. also called the Empire of Iranians (8) |
| FINN | - MacCool; legendary Irish warrior said to have thrown a clod that became the Isle of Man and created the Giant's Causeway as steps to Scotland (4) |
| SAMMCGEE | The Cremation of ___ ___ (1907 poem by 'Bard of the Yukon' Robert Service) |
| RUNES | The characters of an ancient Germanic alphabet, in use, especially in Scandinavia, from the 3rd Century to the Middle Ages (5) |
| PARTHIA | Country in ancient Asia, southeast of the Caspian Sea, destroyed by the Sassanids in the 3rd century |
| FRANKS | Germanic-speaking people from the lower Rhine area (3rd century AD), later becoming a dominant force in Europe (6) |
| CECILIA | Patron saint of music, martyred in the 2nd or 3rd century AD; feast day, 22 November (7) |
| CCI | Start of the third century |
