This term has two meanings.
1. At the end of the 1960s, when most fantasy – whatever its nature – was marketed for children, Lin Carter began editing the Ballantine Adult Fantasy series of reprints, including work by Lord Dunsany, George MacDonald and others, most of whom he claimed to have "rediscovered", and all of whom he claimed (rightly) were authors of adult fiction. In this encyclopedia the simple term Fantasy describes work for adults; we differentiate Children's Fantasy.
2. The term AF has been used to describe erotic or pornographic texts. [JC]