| lowland(noun, level, degree, height) |
| lowness(noun, level, degree, height) |
| minimal(adjective, characteristic, level, grade) |
| minor(adjective, characteristic, level, grade) |
| profundity(noun, level, degree, height) |
| rock-bottom(adjective, characteristic, level, grade) |
| substratum(noun, base, bottom, nadir, rock bottom) |
| underneath(noun, base, bottom, nadir, rock bottom) |
| underside(noun, base, bottom, nadir, rock bottom) |
| crater(verb, decline, crash, dip, descend) |
| decline(verb, crash, dip, descend, crater) |
| descend(verb, decline, crash, dip, crater) |
| dive(verb, decline, crash, dip, descend) |
| drop(verb, decline, crash, dip, descend) |
| lower(verb, decline, crash, dip, descend) |
| nose-dive(verb, decline, crash, dip, descend) |
| plummet(verb, decline, crash, dip, descend) |
| sink(verb, decline, crash, dip, descend) |
| skid(verb, decline, crash, dip, descend) |