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.]
   [1913 Webster]
   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.
      [1913 Webster]

            'T is the obstructed paths of sound shall clear.
                                                  --Pope.
      [1913 Webster]

   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.
      [1913 Webster]

   Syn: To bar; barricade; stop; arrest; check; interrupt; clog;
        choke; impede; retard; embarrass; oppose.
        [1913 Webster]

WordNet (r) 3.0 (2006):

obstructed
    adj 1: shut off to passage or view or hindered from action; "a
           partially obstructed passageway"; "an obstructed view";
           "justice obstructed is not justice" [ant: unobstructed]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "obstructed":
   arrested, back, backward, behindhand, belated, blocked, bound,
   choked, choked up, clogged, clogged up, congested, constipated,
   costive, delayed, delayed-action, detained, foul, fouled, full,
   held up, hung up, in a bind, in abeyance, infarcted, jammed, late,
   latish, moratory, never on time, obstipated, overdue, packed,
   plugged, plugged up, retarded, slow, stopped, stopped up, stuffed,
   stuffed up, tardy, unpunctual, unready, untimely