What does a little blue mean?

Answer 1

When you ask someone how they are feeling and they say "A little blue" they mean they are feeling a bit sad.

When you are mixing a green colour and your art teacher says add "a little blue" it means the colour is somewhat unbalanced in the direction of yellow and a small amount of blue pigment will correct the problem.

When you are asked about the roan you are riding, "a little blue" means your horse is a grey colour.

Answer 2

"Feeling a little blue" is a colloquial expression that means feeling sad or melancholic. It's often used to describe a mild or temporary feeling of sadness.