The Collaborative International Dictionary of English v.0.48:
Obstruct \Ob*struct"\, v. t. [imp. & p. p. Obstructed; p. pr.
& vb. n. Obstructing.] [L. obstructus, p. p. of obstruere
to build up before or against, to obstruct; ob (see Ob-) +
struere to pile up. See Structure.]
1. To block up; to stop up or close, as a way or passage; to
place an obstacle in, or fill with obstacles or
impediments that prevent or hinder passing; as, to
obstruct a street; to obstruct the channels of the body.
'T is the obstructed paths of sound shall clear.
2. To be, or come, in the way of; to hinder from passing; to
stop; to impede; to retard; as, the bar in the harbor
obstructs the passage of ships; clouds obstruct the light
of the sun; unwise rules obstruct legislation. "Th'
impatience of obstructed love." --Johnson.
Syn: To bar; barricade; stop; arrest; check; interrupt; clog;
choke; impede; retard; embarrass; oppose.
Moby Thesaurus II by Grady Ward, 1.0:
130 Moby Thesaurus words for "obstruct":
arrest, backpedal, backwater, bar, barricade, beat off, bind,
block, block out, block up, blockade, bolt, brake, bung, caulk,
check, chink, chock, choke, choke off, choke up, clip the wings,
clog, clog up, close, close off, close tight, close up, confine,
congest, constipate, constrict, cork, counter, cover, crowd, curb,
dam, dam up, debar, decelerate, delay, detain, dog, drag,
draw rein, drive back, ease off, ease up, fend, fend off, fill,
fill up, forbid, foul, halt, hamper, hinder, hold at bay,
hold back, hold in check, hold off, hold up, impede,
interfere with, interrupt, jam, keep at bay, keep back, keep off,
lag, let down, let up, lock, lose ground, lose momentum,
lose speed, make late, moderate, obstipate, occlude, pack, parry,
plug, plug up, preclude, prevent, prohibit, push back, put back,
rebuff, reef, rein in, relax, repel, repulse, retard, set back,
shroud, shut off, shut out, shut tight, slack off, slack up,
slacken, slow, slow down, slow up, spile, squeeze, squeeze shut,
stall, stanch, stave off, stay, stench, stifle, stop, stop up,
stopper, stopple, strangle, strangulate, stuff, stuff up,
suffocate, take in sail, throttle down, turn aside, ward off