La plus que lente
The title, La plus que lente, refers to a slow waltz, the valse lente genre that Debussy tried to copy. It does not refer to the speed of the piece. This piece is a typical example of how Debussy named his pieces. It is also a reaction to the slow waltz, which was very popular in France at the time.  Frank Howes noted, "La plus que lente is, in Debussy's wryly humorous way, the valse lente [slow waltz] to outdo all others."