an obstruction that stands in the way (and must be removed or surmounted or circumvented)
something immaterial that stands in the way and must be circumvented or surmounted; "lack of imagination 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"
a basic truth or law or assumption; "the principles of democracy"
a rule or law concerning a natural phenomenon or the function of a complex system; "the principle of the conservation of mass"; "the principle of jet propulsion"; "the right-hand rule for inductive fields"
a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct; "their principles of composition characterized all their works"
a rule or standard especially of good behavior; "a man of principle"; "he will not violate his principles"