arch dam, arm, armor, armor-plate, backstop, balustrade, bamboo curtain, bank, bar, barbed wire, barrage, barricade, barrier, battle, bear-trap dam, beaver dam, block, blockade, bluff, boom, boundary, brattice, breakwater, breastwork, brick wall, buffer, buffer state, bulkhead, bulkhead in, bulwark, bumper, cage, castellate, cliff, cloison, close in, cofferdam, collision mat, contravallation, coop, corral, crag, crenellate, cushion, dam, defense, diaphragm, dig in, dike, dissepiment, ditch, divide, dividing line, dividing wall, division, earthwork, embankment, embattle, entrench, envelop, escarpment, face, fence, fence off, fences, fender, fortify, garrison, gate, gravity dam, groin, hedge, hedgerow, hem, hoarding, hydraulic-fill dam, immure, interseptum, iron curtain, jam, jetty, leaping weir, levee, logjam, man, man the garrison, mat, midriff, midsection, milldam, mine, moat, mole, mound, pad, pale, paling, palisade, palisades, panel, parapet, paries, partition, party wall, picket, portcullis, precipice, property line, rail, railing, rampart, retaining wall, roadblock, rock-fill dam, scar, scarp, seawall, separate, separation, septulum, septum, set apart, shock pad, shutter dam, steep, stockade, stone wall, stop, trellis, vallation, vallum, wall off, weir, wicket dam, work, zigzag fence
refuge, sanctuary, retreat, fastness, acropolis, keep, last resort, ward, prison, asylum, ark, home, refuge for the destitute, almshouse, hiding place, sanctum sanctorum, roadstead, anchorage, breakwater, mole, port, haven, harbor, harbor of refuge, seaport, pier, jetty, embankment, quay, covert, cover, shelter, screen, lee wall, wing, shield, umbrella, barrier, dashboard, dasher, wall, fort, anchor, kedge, grapnel, grappling iron, sheet anchor, killick, mainstay, support, cheek, ballast, jury mast, vent-peg, safety valve, blow-off valve, safety lamp, lightning rod, lightning conductor, safety belt, airbag, seat belt, antilock brakes, antiskid tires, snow tires, means of escape, lifeboat, lifejacket, life buoy, swimming belt, cork jacket, parachute, plank, steppingstone, emergency landing, safeguard, any port in a storm, bibere venenum in auro, valet anchora virtus.
hindrance, prevention, preclusion, obstruction, stoppage, embolus, embolism, infarct, interruption, interception, interclusion, hindrance, impedition, retardment, retardation, embarrassment, oppilation, coarctation, stricture, restriction, restraint, inhibition, blockade, interference, interposition, obtrusion, discouragement, discountenance, impediment, let, obstacle, obstruction, knot, knag, check, hitch, contretemps, screw loose, grit in the oil, bar, stile, barrier, turnstile, turnpike, gate, portcullis, beaver dam, trocha, barricade, wall, dead wall, sea wall, levee breakwater, groyne, bulkhead, block, buffer, stopper, boom, dam, weir, burrock, drawback, objection, stumbling-block, stumbling-stone, lion in the path, snag, snags and sawyers, encumbrance, incumbrance, clog, skid, shoe, spoke, drag, drag chain, drag weight, stay, stop, preventive, prophylactic, load, burden, fardel, onus, millstone round one's neck, impedimenta, dead weight, lumber, pack, nightmare, Ephialtes, incubus, old man of the sea, remora, difficulty, insuperable, obstacle, estoppel, ill wind, head wind, trammel, tether, hold back, counterpoise, damper, wet blanket, hinderer, marplot, killjoy, party pooper, party crasher, interloper, trail of a red herring, opponent, hindering, obstructive, obstruent, impeditive, impedient, intercipient, prophylactic, impedimentary, in the way of, unfavorable, onerous, burdensome, cumbrous, cumbersome, obtrusive, hindered, windbound, waterlogged, heavy laden, hard pressed, unassisted &c (assist), single-handed, alone, deserted, occurrent nubes.
prison, prison house, jail, gaol, cage, coop, den, cell, stronghold, fortress, keep, donjon, dungeon, Bastille, oubliette, bridewell, house of correction, hulks, tollbooth, panopticon, penitentiary, guardroom, lockup, hold, round house, watch house, station house, sponging house, station, house of detention, black hole, pen, fold, pound, inclosure, isolation (exclusion), penal settlement, penal colony, bilboes, stocks, limbo, quod, calaboose, chauki, choky, thana, workhouse, Newgate, Fleet, Marshalsea, King's Bench, Queen's Bench, bond, bandage, irons, pinion, gyve, fetter, shackle, trammel, manacle, handcuff, straight jacket, strait jacket, strait-jacket, strait-waistcoat, hopples, vice, vise, yoke, collar, halter, harness, muzzle, gag, bit, brake, curb, snaffle, bridle, rein, reins, bearing rein, martingale, leading string, tether, picket, band, guy, chain, cord, cavesson, hackamore, headstall, jaquima, lines, ribbons, bolt, deadbolt, bar, lock, police lock, combination lock, padlock, rail, wall, stone wall, paling, palisade, fence, picket fence, barbed wire fence, Cyclone fence, stockade fence, chain-link fence, barrier, barricade, drag.
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.
lining, inner coating, coating, stalactite, stalagmite, filling, stuffing, wadding, padding, wainscot, parietes, wall, lined.
inclosure, envelope, case, wrapper, girdle, pen, fold, pen fold, in fold, sheep fold, paddock, pound, corral, yard, net, seine net, wall, hedge, hedge row, espalier, fence, pale, paling, balustrade, rail, railing, quickset hedge, park paling, circumvallation, enceinte, ring fence, barrier, barricade, gate, gateway, bent, dingle, door, hatch, cordon, prison, dike, dyke, ditch, fosse, moat.