What is a synonym for the word dense?

The best synonym for "dense" depends on the context. Here are some options:

For describing physical density:

* Compact

* Thick

* Solid

* Concentrated

* Heavy

For describing intellectual density:

* Intelligent

* Smart

* Sharp

* Brilliant

* Astute

* Knowledgeable

For describing something difficult to understand:

* Opaque

* Confusing

* Complex

* Abstruse

* Obscure

For describing something crowded or congested:

* Packed

* Crowded

* Congested

* Thickly populated

For describing something full of something:

* Rich

* Full

* Packed

* Saturated

Please provide more context if you need a more specific synonym.