Meaning : Something immaterial that stands in the way and must be circumvented or surmounted.
Example :
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.
Synonyms : obstruction
Meaning : An obstruction that stands in the way (and must be removed or surmounted or circumvented).