He was blindsided by a bike that suddenly appeared around the corner.

blindsided 是动词 blindside 的过去分词形式。blindside 由 blind（盲目的）和 side（侧面）组成，字面意思是"从盲区攻击"，引申为"出其不意地袭击"或"使措手不及"。 在句中表示被动含义，指"被突然袭击/被撞个措手不及"。