J
Jig
The jig (= French: gigue; Italian: giga), a lively
dance in compound time, became the usual final dance of the baroque dance
suite.
Jota
The jota is a traditional Spanish dance, transmuted
into an orchestral composition by the Russian composer Glinka in his Jota
aragonesa.
Just Intonation
Singing or instrumental playing in what is said to
be a pure, natural scale, not that which is artificially fixed on keyboard
instruments by Equal Temperament.
One other "natural" tuning system is the Pythagorean
system.