| basin(noun, drop, area, decline, fall) |
| depression(noun, drop, decline, fall, dish) |
| hollow(noun, drop, area, decline, fall) |
| concavity(noun, drop, decline, fall, depression) |
| excavation(noun, depression, impression, hollow) |
| sink(noun, drop, decline, fall, depression) |
| bowl(noun, depression, dish, impression, sink) |
| dimple(noun, depression, impression, hollow) |
| gulf(noun, dish, sink, pot) |
| hole(noun, drop, decline, fall, depression) |
| scoop(noun, depression, impression, hollow) |
| sinkhole(noun, drop, decline, fall, depression) |
| valley(noun, depression, dish, impression, sink) |
| bottom(noun, cavern) |
| cave(noun, bottom, cavern) |
| cavern(noun, bottom) |
| cavity(noun, impression, hollow, pocket) |
| channel(noun, bottom, cavern) |
| cleft(noun, bottom, cup, indentation) |
| crater(noun, depression, impression, hollow) |