in Chinese, can 老外 be translated as "amateur"?

老外 is most of the time referring to foreigner.

It may vaguely pass as "outsider of a trade / skill". Meaning that someone who does not know the trade / skill at all.

If you are an "amateur" - that means you know a little bit of the trade, then you are NOT really an 老外, you are then 非熟练, meaning not experienced.

i.e. If I play a bit of piano, I may be an amateur 非熟练.
But if I don't know how to play the piano at all, I am or as you may put it 老外

amateur translated as "外行"

if a chinese call that to a foreigner then obviously it means that that person is a foreigner

if a chinese call that to another chinese..it may mean

a) amateur- they have no idea about what they are going on about
b) to be mean ..a b #$%**** artist
c)someone who is not familiar with the situation but feel the need to pretend that they are smart

the "外" in 老外 means "outside"

So 老外 means outsider or foreigner. Chinese people will refer to any foreigner as 老外.

If one Chinese uses this word to call another Chinese, then he's mocking him for his lack of understanding of the Chinese way (ie. he's behaving like a outsider).

Yes. You are right. 老外 can mean 'amateur', but is very a unusual usage.

Well, difinitely it is wrong! Amateur means layman and unprofessional while 老外 means foreigners!

It's probably an old usage of the word. Now that China is used to seeing foreigners, the primary meaning of 老外 is "foreigner", as in someone who does not look Asian. The "amateur" sense of the word isn't usually used any more, and has been replaced by 外行.

Yeah, but it's unusual.
老外 just means foreigners in oral Chinese I think.
As for amateur, we always say "菜鸟" or "新手".

I stayed in China for a long time and foreigners, everyone, misunderstand it. "Laowai" refers to foreigners of European ancestry. Or it other words, refers to "Whites". It's not a bad word. 外行 is not related, you should consider changing your dictionary. 外行 means a person who has no idea in certain profession or field.

Laowai in Chinese means foreigner, white or black foreigners are all called "Laowai" by Chinese