What does "Gauckerl" mean in the Austrian dialect?

It may also be spelled "Gaukerl."

Are you talking about Mozart's dog? He (or she, the sex doesn't seem to have been recorded) was named "Gaukerl", which was somtimes also spelled "Gauckerl".

I don't believe it is a real word, more a punny name, like my cats "Furocious" and "LucyFur".

"Gaukeln" originally meant to sway or flutter. It might be said of a kid on a swing or a butterfly. A secondary meaning is to cheat or use sleight-of-hand, like doing fake magic or rigged games of chance. A person who does that would be called a "Gaukler".

The "-erl" is a diminutive suffix used for endearments in some parts of Austria, where my friends might call me "Liserl". But "Kerl" also means "guy" or "fellow", and might be used on a male dog that has been bad or mischievous ("Du Kerl", like we mightt say "you bad guy").

So, putting all that together, the dog might have had a swaying walk or been a con artist, the name was probably intended as a diminutive, and there may have also been a pun on "Kerl".

Umm... i don't really know but i recommend you to visit the page below, it would help you i think. (first, make sure of the exact spelling of this word please)

It is not very common to use "Gauckerl" in Austria. Basically, the only historic source of this expression is the dog of Wolfgang Amadeus Mozart (you see, even his dog is famous over here *ggg*) and still the name sometimes is used as a name for animals like dogs and horses.
In Viennese dialect, the word sometimes, but very rarely is used for telling somebody that he is not that important as he may think about himself. For example, if a young guy tells his girlfriend that he is able to climb a high mountain within a very short time, she would answer, "a geh, du Gaukerl!" what is equivalent to "dont tell stories, you little bragger!" - but in a friendly way.
You won't hear this expression too often here in Austria...