Of blue color, like clear sky or deep sea.

• Having a blue tint or look.

The color blue.

• The hue of clear sky or deep ocean.

Depressed or sad.

• Feeling melancholy.

Bluish from lack of oxygen; cyanotic.

• Skin appearing blue or purplish.

Of a party represented by blue.

• In the U.S.: of the Democratic Party.

Of meat: very rare; barely cooked.

• Seared outside, cool and nearly raw inside.

To make or become blue; to turn blue.

• To take on a bluish color.

To treat steel so it resists rust; to blue.

• Apply a chemical or heat process to form a blue oxide.