From The Art and Popular Culture Encyclopedia
Freak folk is a genre of folk music associated with contemporary artists, like Devendra Banhart, Joanna Newsom, Hecuba, Akron/Family, Rio en Medio, Sufjan Stevens and with '60s artists like the Holy Modal Rounders, The Incredible String Band, Tyrannosaurus Rex, The Godz and The Fugs. It is related to, but distinct from, psych folk.
Musically, it consists of mainly acoustic instruments, mostly guitar and occasionally violin or flute, accompanied by percussion instruments such as bongos. The guitar often uses alternate tunings. The drone is a component of the style.
The term "Freak Folk" is largely a music journalist created phrase for the genre and hasn't been adopted or endorsed by the artists themselves. Although many of the artists have shrugged off defining their movement by a specific genre, several have proposed alternatives such as "Naturalismo," that evade the negative connotations some have come to associate with the "Freak Folk" genre and collective of musicians.