| Rating | Solver | Clue |
|---|---|---|
| SUBTLE | Rarefied | |
| RAREFIABLE | Capable of being rarefied. | |
| ATTENUATED | Made thin or less viscid; rarefied. | |
| PNEUMOTHERAPY | The treatment of disease by inhalations of compressed or rarefied air. | |
| RAREFACTION | The act or process of rarefying; the state of being rarefied; -- opposed to condensation; as, the rarefaction of air. | |