Despite the lack of physical evidence, he was convicted primarily on the testimony of a single witness.

convicted 是动词 convict 的过去分词形式。convict 由前缀 con-（表示"完全、加强"）和词根 vict（来自拉丁语 vincere，意为"征服"）组成，原意是"彻底征服"，引申为法律意义上的"定罪"。在句中作为被动语态使用，表示"被定罪"。