a.

1. 密集的，稠密的
   We fought our way through dense forest.

   我们奋力通过密林。

2. （烟，雾等）浓厚的
   Traffic slowed down because of the dense fog.

   因浓雾车辆减速行驶。

3. 愚钝的
   He is so dense he'll never amount to anything.

   他十分愚钝，决不会有出息。

adj.

1. closely compacted in substance.
   ▸crowded closely together.
2. informal (of a person) stupid.