No such word in UK English, it's simply got. However, our American pals like to add the extra (although they usually prefer to simplify and deduct additional letters) and so say gotten.
It got [sic] me thinking though, we do we then have the saying "ill-gotten gains"?
Seems this is the closest I found to a suitable answer- ta to Jakub Marian's:
Let’s not beat around the bush with complicated linguistic terms; the difference between “got” and “gotten” is relatively simple.
If you learn British English, just use “got” and avoid “gotten” altogether.
There is no such word as “gotten” in British English, and perhaps the only British expression containing the word is “ill-gotten”, which is an adjective meaning “obtained illegally or unfairly”.
If you learn American English, the situation is slightly more complicated. The past tense of “get” is “got”, just as in British English, but you should remember that:
In American English, the past participle of “get” in its literal sense of “receive” or “become” is usually “gotten”. In the sense of “must” or “have”, the past participle is always “got”.
For example, in the first case (receive, become):
I have never gotten good grades. (= I have never received good grades.)
I’ve gotten interested in chess. (= I’ve become interested in chess.)
And in the second case (have, have to):
She’s got five children. (= She has five children)
I’ve got to go now. (= I must go now.)
Note that “have got” in the sense of “have”, “possess” is more common in British English and is often considered colloquial or even incorrect in American English. Also note that there are regional differences, and some Americans prefer “got” in the first case as well, but on average, the “gotten” form in the sense of “receive” and “become” is much more common than “got” in the US.
But then we also have another "phrase" that makes me gnash my teeth, when we have a TV copper arriving at the scene of a crime uttering the phrase:
"What do/have we got?"
Aside from the appalling "do we got" killing any semblance of correct grammar or decent English, why do they then not say "gotten"?
No consistency either...