Someone who works to a company without social security link. A way to avoid costs hiring people for a long time. A kind of reducing costs strategy.
Normally VENDOR works like normal employees but has no Vacation, Bonus , etc...
A group of workers that get some prejudice sometimes, because they work better than the regular employees exposing their weakness to their bosses.
* These videos are coming directly from Youtube, they may or may not be most relevant to the word "Vendor"