filk1
/fɪlk/noun
Among science fiction and fantasy fans: a type of popular music, commonly performed at fan conventions, characterized by the use of familiar or traditional songs whose lyrics have been rewritten or parodied (usually on themes drawn from science fiction or fantasy writing), or sometimes original songs with similar content. Chiefly attributive, especially as filk song, filk-singing, etc.
Origin
1950s. Probably originally a transmission error for folk.
filk2
/fɪlk/verb
[no object] Among science fiction and fantasy fans: to write or perform filk songs.
Origin
1990s; earliest use found in Larry Niven (b. 1938). From filk.