What is a RINO?

What is a RINO to you. I know it means republican in name only. What policies make one republican? That socially liberal person who advocates for small gov and classifies himself as republican is imo republican

As the title says what classifies someone as a RINO everyone probably has a different definition for it so I want to know.

I have been called a RINO and I’ve also been called right wing so clearly someone is wrong. I’m really just looking for perspective on this

Edit 1: an example is Charlie baker he gets called a RINO, but he definitely isn’t