Let's get this straight right now: In the US the Webster 1913 definition is the valid one. Lemonade in the US of A is a drink of lemons, sugar and water, served chilled or on ice, usually from a pitcher on a porch, or perhaps, a veranda. American lemonade is cloudy in appearance due to particulates in the lemon juice.

In the UK and from my experience the rest of Europe, lemonade is a carbonated beverage that is clear, and tastes of lemon. The closest thing we have to that are things like Sprite or Seven-Up, but those are decidedly lemon-lime flavored drinks, which is actually quite different.

This is one of the strange situations where the British version of somehing is inferior to the American one. Brits, when you come to America, hie thee to a Hot Dog on a Stick in the mall and have them draw you a glass of lemonade from the clear plastic dispenser in which you can clearly see the ice and lemons, and enjoy.

Note however, that lemonade (US) will make you thirsty, again because of that pesky lemon juice tickling the back of your throat.