Related Clues:

• ___ as a rock
• Neither liquid nor gas
• Not shaky
• Sphere or cube
• Logically sound
• Cube or sphere
• Not striped, as a billiard ball
• 'Easy now ...'
• Unhyphenated
• Reliable, as a citizen
• Nonliquid state
• Sturdily built
• Chock-a-block
• Parallelepiped, e.g.
• Densely built