Related Clues:

• Indifferent to pleasure or pain
• Hard-boiled
• Covered with rocks
• Like Spock
• Hardly welcoming
• Even-keeled
• Lacking compassion
• One who bites the bullet
• Lacking expression
• Phlegmatic
• Bullet-biting type
• One who never cries 'Ow!'
• Like some silences
• Immovable type
• Pebble-strewn