A well-known "elliptical" wing:

^{One of the 50 Spitfire still flying in the World. Source}

My questions

• What is elliptical in the elliptical wing?
• What is regularly distributed: lift? drag? something else?

Elliptical wings are sometimes used:

^{One of the 50 Spitfire still flying in the World. Source}

I read it's because this shape allows a perfect distribution of aerodynamic forces. But actually:

• What is actually elliptical in the elliptical wing?
• What is regularly distributed: Is it lift? or drag? or something else?

Statements I've seen about the elliptical wing:

• This is not the planform which is elliptical, this is the lift distribution.
• Only on an elliptical wing, the drag is regularly distributed. In other cases drag is generally higher near the wingtips.

I don't understand well these two statements. The only thing I have understood is that on the elliptical wing, at any distance from the root, for a constant angle of attack from root to tip:

• Lift/drag ratio is constant
• Lift and drag decrease from root to tip.

^Source

My questions:

• What is elliptical in the elliptical wing?
• What is regular about lift or drag?

A well-known "elliptical" wing:

^{One of the 50 Spitfire still flying in the World. Source}

My questions

• What is elliptical in the elliptical wing?
• What is regularly distributed: lift? drag? something else?