| obstacle |
| parapet(noun, support, cover, position, block) |
| redoubt(noun, support, cover, position, guard) |
| seawall |
| secure(verb, support, hold, close, cover) |
| battlement(noun, support, defense, barricade, wall) |
| breastwork(noun, support, rock, defense, elevation) |
| cover(verb, support, hold, keep, maintain) |
| earthwork(noun, support, defense, fortification, barricade) |
| security(noun, support, cover, position, care) |
| trench(noun, cover, position, guard, shield) |
| boom |
| fence(noun, cover, position, block, bar) |
| fend(verb, support, close, cover, separate) |
| groyne |
| mound(noun, defense, elevation, fortification, wall) |
| outwork(noun, support, fortification, embankment, earthwork) |
| safety(noun, care, guard, shield, shelter) |
| vallation(noun, support, defense, elevation, fortification) |
| bank |