(そがい) A physical obstacle (a tree in the road) 阻害物 (そがいぶつ).
(ぼうがい) Interference. (Used with people, not objects like 阻害 (そがい).)
(ししょう) An obstacle to a plan: “There were so many obstacles we had to overcome to arrange this wedding – finding the right venue, getting affordable silverware, trying to find a band that knew how to play ‘ace of spades,’ etc.”
まとい(あしでまとい) A weak link: A person who holds back the team.   PPP