Someone parked their car in the middle of the road to obstruct the traffic.

obstruct 是动词，由前缀 ob-（表示"反对、阻挡"）和词根 struct（来自拉丁语 struere，意为"建造"）组成，字面意思是"阻挡建造"，引申为"阻碍、阻挡"的意思。在句中指"故意阻挡交通"。