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.
1950s. Probably originally a transmission error for folk.
Among science fiction and fantasy fans: to write or perform filk songs.
1990s; earliest use found in Larry Niven (b. 1938). From filk.