1. past tense and past participle of blue; made blue or bluish in color
2. treated metal with heat to create a protective blue-black finish
Usage: metalworking

1. having been made blue or having a blue tint

Examples

• The steel was blued to prevent rust.
• She blued the white fabric with a special dye.
• The gunsmith blued the barrel of the rifle.
• The blued metal gleamed in the sunlight.
• He carefully blued the knife blade for protection.
• The blued finish gave the tool a professional appearance.