His silence was perceived as disagreement by everyone.

perceived 是动词 perceive 的过去分词形式，在句中表示被动。perceive 由前缀 per-（表示"完全、彻底"）和词根 ceive（来自拉丁语 capere，意为"抓住、理解"）组成，意思是"察觉、理解、认为"。perceived 在这里表示"被理解为"。