The road was completely blocked by another overturned truck.

overturned 是动词 overturn 的过去分词形式，overturn 由前缀 over-（表示"翻转"）和动词 turn（转动）组成，意思是"翻倒、倾覆"。 truck 是名词，指"卡车"，一种用于运输货物的大型车辆。