“扩散”的意思是东西或消息从一个地方向四周散开，越来越大或越来越多。

"扩散" means things or information spread out from one place in all directions, becoming bigger or more numerous.

我们常说消息扩散、病毒扩散或者烟味扩散。

We often say information 扩散, viruses 扩散, or smoke smell 扩散.