| Actinium | actinium |
| Actinoid | actinide actinoid |
| Actionfilm | action film |
| Artinskium | Artinskian |
| Arminius | Arminius |
| Ladinium | Ladinian |
| Minium | minium |
| Aluminium | aluminium aluminum |
| Aeronium | Aeronian |
| Antonius | Antonius |
| Bartonium | Bartonian |
| Santonium | Santonian |
| Titonium | Tithonian |
| Aalenium | Aalenian |
| Ammonium | ammonium |
| Cranium | cranium |
| Aptium | Aptian |
| Atrium | atrium |
| Action | action |
| active | actively |