| close(hard, tough, solid, rigid, inflexible) |
| impenetrable(hard, solid, rigid, resistant, impervious) |
| impermeable(adjective, hard, solid, rigid, resistant) |
| compact(hard, solid, rigid, density) |
| dense(hard, solid, rigid, resistant, impervious) |
| firm(adjective, hard, solid, rigid, inflexible) |
| concrete(hard, tough, solid, rigid, inflexible) |
| thick(hard, solid, rigid, syrupy, jellied) |
| hard(tough, solid, rigid, inflexible, density) |
| massive |
| solid(hard, rigid, resistant, impervious, density) |
| substantial(hard, solid, rigid, density) |
| compressed(hard, tough, solid, rigid, inflexible) |
| concentrated(hard, tough, solid, rigid, inflexible) |
| condensed(hard, tough, solid, rigid, inflexible) |
| gluey |
| heavy(hard, tough, solid, rigid, inflexible) |
| incompressible(adjective, firm, density) |
| serried |
| thickset |