The CNC kink is already one of the most extreme preferences that can be found in the BDSM field. The meaning of CNC is not so easy to explain. Pronounced / written out it means "consensual non consent". This means as much as agree to something that you do not agree
The term sadomasochism is mainly used by the media and is hardly represented in the BDSM scene. This is partly due to the rather negative connotation of the word, but also because sadism and masochism are only a small variation of BDSM.