abbreviation, approach, astriction, astringency, asymptote, bar, barrier, blank wall, blind alley, blind gut, block, blockade, blockage, canal, catch, cecum, cervix, channel, choking, choking off, circumscription, clog, coarctation, collision course, compactedness, compaction, compression, compressure, concentralization, concentration, concourse, concurrence, condensation, confluence, conflux, congestion, congress, consolidation, constipation, constriction, constringency, contraction, contracture, convergence, converging, cordon, costiveness, crossing, cul-de-sac, curtailment, curtain, dead end, decrease, defile, determent, deterrent, difficulty, diminuendo, drawback, embolism, embolus, focalization, focus, funnel, gorge, hang-up, hazard, hitch, hourglass, hourglass figure, hub, hurdle, impasse, impediment, infarct, infarction, isthmus, jam, joker, knitting, meeting, mutual approach, narrow, narrow place, narrowing, narrowing gap, narrows, neck, objection, obstacle, obstipation, obstruction, obstructive, one small difficulty, pass, puckering, pursing, radius, reduction, rub, sealing off, shortening, snag, solidification, spokes, stop, stoppage, strait, stranglement, strangulation, striction, stricture, stumbling block, stumbling stone, systole, tangent, throat, wasp waist, wrinkling