Related Clues:

• Like a blockhead
• Dimwitted
• In a clumsy manner
• Short on sharpness
• Like a stereotypical palooka
• Like molasses
• Clumsy
• Like osmium, more than any other known element
• Hard to penetrate
• Moronic
• Idiotic
• Crammed
• Needs another way?
• Concentrated
• None too swift