It's the new "C" word according to Melissa Francis, co-host of CNBC's "The Call." Using the word "cartel" to describe OPEC is officially a no- no.

Francis, who was on location in Vienna, Austria at the OPEC summit, reported on an exchange between herself and Ali Al-Naimi, the oil minister of Saudi Arabia during the May 28 broadcast of "Squawk on the Street." In an interview, Al-Naimi took issue with Francis using the word "cartel" to describe OPEC:

Francis: When do you think we'll hit that $75-to-80 range that seem like almost everybody in the cartel agrees is sort of the equilibrium price?

Al-Naimi: You have to be careful calling OPEC a cartel. I resent that.