FZ meaning in Messaging ?

In popular culture, the friend zone (or friendzone) is a conceptual place describing a situation in which one person in a mutual friendship wishes to enter into a romantic or sexual relationship with the other person, while the other does not. The person whose romantic advances were rejected is then said to have "entered" (or to have been "put in") the friend zone, with the sense that they are stuck there.

The concept of the friend zone has been criticized as misogynistic, because of a belief that the concept implies an expectation that women should be romantically involved with men in whom they have no interest, simply because the men were nice to them, though the term refers to all forms of unrequited affection, not necessarily a man liking a woman. It is also closely associated with so-called "nice guy syndrome".

The term was originally popularized in the American sitcom television series Friends (1994). In the seventh episode, The One with the Blackout, Ross is lovesick for Rachel, but according to Joey, when two people meet, there is a short period in which there is potential for a romantic relationship that Ross has gone beyond. After this time, if they continue to see each other, they are in the "friend zone" and so a romantic relationship is effectively impossible, even if one of the parties wishes for it to be possible.