| concave |
| cut(noun, break, crack, depression, score) |
| dental caries(noun, expression, idiom) |
| dint(depression, hollow, scrape, indentation, chip) |
| fissure(noun, break, cut, crack, opening) |
| fossa |
| hiatus(noun, break, opening, breach, space) |
| hollowness(noun, opening, void, hollow, emptiness) |
| interval(noun, break, opening, breach, space) |
| niche(noun, break, cut, crack, hole) |
| orifice(noun, break, cut, opening, breach) |
| quarry(noun, mine, pit) |
| split(noun, breach, hole, hollow, gap) |
| tooth decay(noun, expression, idiom, decay) |
| abysm |
| arroyo(noun, break, opening, breach, void) |
| atrium(noun, area, space, hole, hollow) |
| box(noun, opening, space, hollow, room) |
| burrow(noun, container, mine, pit, chamber) |
| canyon(noun, break, opening, breach, hole) |