What is a "professional" lens?

[Frog]

I maybe should have asked what a 'qulity' lens is. I realize that 'pro' is basically meaningless.
Just look at all those professional tripods for sale on ebay for 10 bucks.

[freygr]

I maybe should have asked what a 'qulity' lens is. I realize that 'pro' is basically meaningless.
Just look at all those professional tripods for sale on ebay for 10 bucks.

Now there is a joke

There is a saying: You Get what you pay for