Definitions of obstruction:

• noun:   getting in someone's way
• noun:   the act of obstructing

  Example: "Obstruction of justice"

• noun:   any structure that makes progress difficult
• noun:   the state or condition of being obstructed
• noun:   something immaterial that stands in the way and must be circumvented or surmounted

  Example: "The filibuster was a major obstruction to the success of their plan"