Related Clues:

• Merged
• A little on the slow side
• Not sparse
• Bonded
• Not Mensa material
• American airline
• Compacted
• Like thickets
• Not the sharpest pencil in the box
• Affiliated
• Not very sharp
• A few bricks shy of a load
• Highly concentrated
• Half of the U.S.?
• Tough to get through to