Source : Webster's Revised Unabridged Dictionary (1913)

Obstruction \Ob*struc"tion\, n. [L. obstructio.]
   1. The act of obstructing, or state of being obstructed.

   2. That which obstructs or impedes; an obstacle; an
      impediment; a hindrance.

            A popular assembly free from obstruction. --Swift.

   3. The condition of having the natural powers obstructed in
      their usual course; the arrest of the vital functions;
      death. [Poetic]

            To die, and go we know not where, To lie in cold
            obstruction, and to rot.              --Shak.

   Syn: {Obstacle}; bar; barrier; impediment; clog; check;
        hindrance.

   Usage: {Obstruction}, {Obstacle}. The difference between
          these words is that indicated by their etymology; an
          obstacle is something standing in the way; an
          obstruction is something put in the way. Obstacle
          implies more fixedness and is the stronger word. We
          remove obstructions; we surmount obstacles.

                Disparity in age seems a greater obstacle to an
                intimate friendship than inequality of fortune.
                                                  --Collier.

                The king expected to meet with all the
                obstructions and difficulties his enraged
                enemies could lay in his way.     --Clarendon.

Source : WordNet®

obstruction
     n 1: any structure that makes progress difficult [syn: {obstructor},
           {obstructer}, {impediment}, {impedimenta}]
     2: the state or condition of being obstructed [syn: {blockage}]
     3: something immaterial that stands in the way and must be
        circumvented or surmounted; "lack of immagination is an
        obstacle to one's advancement"; "the poverty of a district
        is an obstacle to good education"; "the filibuster was a
        major obstruction to the success of their plan" [syn: {obstacle}]
     4: the act of obstructing; "obstruction of justice"
     5: getting in someone's way