chaconne

n. musical piece in 3/4 over a ground bass; dance performed to this music

In music, a chaconne (; Italian: ciaccona) is a musical form whose primary formal feature involves variation on a repeated short harmonic progression. Originally a quick dance-song from Spain, with rather indelicate text, the chaconne eventually became a slow triple meter dance which first emerged in the 16th century. The chaconne is understood today — in a rather arbitrary way — to be a set of variations on a harmonic progression, as opposed to a set of variations on a melodic bass pattern (to which is likewise artificially assigned the term passacaglia). In actual usage in music history, the term "chaconne" has not been so clearly distinguished from passacaglia as regards the way the given piece of music is constructed.
See more at Wikipedia.org...

(n.)
An old Spanish dance in moderate three-four measure, like the Passacaglia, which is slower. Both are used by classical composers as themes for variations.