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"
the only surviving hominid; species to which modern man belongs; bipedal primate having language and ability to make and use complex tools; brain volume at least 1400 cc