NCAA athletes are considered amateur. I experienced a tradition of European sports clubs (particularly in Germany) which were amateur, community multisport clubs with for-profit penthouse suites like VfL Wolfsburg. Amateur is what you are if you do something a) without education in it and b) without getting paid for it. And yet people run scared of the word.
To be fair this phenomenon is not unique to the US (The UK, after all, coined "semi-pro" to describe footballers who get paid, but not enough that they don't have to do something else to earn a living)
However, the use of 'amateur' is virtually shunned universally in the US, where you can be a short season A ball baseball player and still be paid.
I consider NPSL to be amateur. The players are not paid, thus allowing those of college age to continue college ball. The season is even timed to encourage college players. The pro-driven Open Cup not so much, and yet the top AMATEUR club every year gets a nice check for such status in that tournament. Ask Christos FC (or Chattanooga FC of...the NPSL)
Side note, the 'semi-pro' trend has also hit the Fargo Invaders American Football team.