ATONAL music: music lacking a tonic, that is, a key or tonal center [noun: ATONALITY]
SPRECHSTIMME: Schoenberg's invention, a singsong vocal technique between singing and speaking
KLANGFARBENMELODIE: literally "tone-color-melody," Schoenberg's name for a melody jumping rapidly from one instrument (and tone color) to another
TWELVE-TONE or DODECAPHONIC composition: Schoenberg's method for writing atonal music based on a specific ordering of the 12 notes in the chromatic scale
TWELVE-TONE ROW: a choice of such an ordering