1. in a way that is closely packed together or crowded
2. in a way that is difficult to understand or penetrate

Examples

• The forest was densely packed with tall pine trees.
• Tokyo is one of the most densely populated cities in the world.
• The fog rolled in densely, making it impossible to see the road.
• Her hair was densely curled and difficult to brush.
• The technical manual was densely written and hard to follow.
• Stars were densely clustered in that region of the galaxy.