THESAURUS
Precipice
bluff, cliff, crag, crest, escarpment, face, hilltop, knoll, lofty peak, mountaintop, palisade, palisades, peak, pic, pico, pike, pinnacle, point, scar, scarp, spur, steep, summit, tor, wall
ROGET THESAURUS
Precipice
Pitfall
N
pitfall, rocks, reefs, coral reef, sunken rocks, snags, sands, quicksands, syrt, syrtis, Goodwin sands, sandy foundation, slippery ground, breakers, shoals, shallows, bank, shelf, flat, lee shore, ironbound coast, rock ahead, breakers ahead, precipice, maelstrom, volcano, ambush, pitfall, trapdoor, trap, sword of Damocles, wolf at the door, snake in the grass, death in the pot, latency, ugly customer, dangerous person, le chat qui dort, firebrand, hornet's nest, latet anquis in herba, proximus ardet Ucalegon.
Verticality
N
verticality, erectness, perpendicularity, right angle, normal, azimuth circle, wall, precipice, cliff, elevation, erection, square, plumb line, plummet, vertical, upright, erect, perpendicular, plumb, normal, straight, bolt, upright, rampant, standing up, rectangular, orthogonal, vertically, up, on end, up on end, right on end, a plomb, endwise, one one's legs, at right angles.