Related Clues:

• Like a thicket
• Like heavy fog
• Closely crowded together
• Knuckleheaded
• Really crammed in
• Slow to catch on
• Crowded together
• Thick, as fog
• Tough to get through
• Like a dumbbell
• Heavy, like some baked goods
• Like a black hole
• Thick, compact or crowded
• Thick, compact
• Thick as undergrowth may be