| cavity(noun, break, area, retreat, opening) |
| hole(noun, break, retreat, opening, sack) |
| pocket(noun, sack, space, box, receptacle) |
| basin(noun, space, hole, hollow, pocket) |
| crater(noun, space, hole, hollow, pocket) |
| hollow(noun, break, area, retreat, opening) |
| depression(noun, break, retreat, space, hole) |
| dimple(noun, dip, bottom, indentation) |
| dip(noun, bottom, indentation, recess) |
| recess(noun, place, low, opening, hole) |
| chamber(noun, sack, space, hole, hollow) |
| nook(noun, break, opening, space, hole) |
| channel(noun, opening, dip, bottom, slit) |
| cleft(noun, space, dip, hole, hollow) |
| excavation(noun, dip, bottom, indentation) |
| groove(noun, opening, dip, bottom, slit) |
| gulf(noun, low, dip, bottom) |
| sinkage(noun, dip, bottom, indentation) |
| sinkhole(noun, dip, bottom, indentation) |
| void(noun, space, hole, hollow, pocket) |