adjective: (music) About or inspired by science fiction, fantasy, horror, science, and/or subjects of interest to fans of speculative fiction; frequently, being a song whose lyrics have been altered to refer to science fiction; parodying. (However, much filk music is original rather than parodic.)
noun: Filk music.
noun: In general
noun: A filk song written as a parody of, or in the form of and with reference to, another song (which need not itself be a filk song). Compare verb transitive sense.
verb: (intransitive) To perform filk music.
verb: (intransitive) To participate in a filk circle, including singing along.