| unyielding(adjective, hard, tough, firm) |
| calcified(adjective, firm, solid, hardened) |
| cemented(adjective, hard, firm, solid) |
| close(adjective, hard, tough, solid) |
| compact(adjective, hard, tough, firm) |
| compressed(adjective, hard, tough, firm) |
| concentrated(verb, adjective, hard, tough) |
| conglomerated(adjective, firm, solid, hardened) |
| consolidated(verb, adjective, firm, solid) |
| crowded(adjective, solid, heavy, deep) |
| deep(adjective, solid, heavy, stiff) |
| dried(verb, adjective, firm, solid) |
| gloppy(adjective, solid, heavy, deep) |
| gummous(adjective, solid, heavy, deep) |
| gunky(adjective, solid, heavy, deep) |
| hard(adjective, tough, firm, solid) |
| heavy(adjective, hard, tough, solid) |
| impenetrable(adjective, hard, tough, solid) |
| impervious(adjective, hard, tough, solid) |
| indurate(adjective, hard, firm, solid) |