Not sure if this was a joke or serious, but 'amateur radio' refers basically to people who are into HAM radio. It doesn't necessarily preclude them from also working with radio professionally.
As per the linked wikipedia article.. it used to mean that (as a pejorative term coming from professional wired telegraphy in the 19th century). From the article ".. by the mid-20th century it had lost its pejorative meaning." But yes, it's not an acronym.
It means ham as in ham fisted, as in amateurish or unskilled.
See the Wikipedia entry for more info https://en.wikipedia.org/wiki/Amateur_radio