One subtype of filk songs is the "ose" song, one on themes of death and gloom. The term derives from the word "morose", as in "ose, morose, even-more-ose".
onE SUbtype of Filk songs Is the "OSE" Song, one on Themes OF deAth aNd glOom. thE TerM derivEs from the worD "moroSe", aS in "osE, morose, evEN-more-ose".