key In TONAL music, the hierarchy of NOTES, CHORDS, and other pitch elements around a central note, the TONIC. There are two kinds of keys, major and minor.
kithara Ancient Greek instrument, a large LYRE.
Klangfarbenmelodie (German, "tone-color melody") Term coined by Arnold Schoenberg to describe a succession of tone colors that is perceived as analogous to the changing pitches in a MELODY.
Kyrie (Greek, "Lord") One of the five major musical items in the MASS ORDINARY, based on a BYZANTINE litany.