Related Clues:

• Compacted
• Like thickets
• Not the sharpest pencil in the box
• Not very sharp
• A few bricks shy of a load
• Highly concentrated
• Tough to get through to
• Hard to get through to
• Like a thicket
• Like heavy fog
• Chummy
• Closely crowded together
• Knuckleheaded
• Really crammed in
• Slow to catch on