Here are 6 Gnossiennes by French composer Erik Satie:

The term is a neologism coined by Satie in the late 19th century for “compositions with a dance-like quality.” Later, to honor his mentor Francis Poulenc also wrote some.

According to Wikipedia:

The word appears to derive from gnosis. Satie was involved in gnostic sects and movements at the time that he began to compose the Gnossiennes. However, some published versions claim that the word derives from Cretan “knossos” or “gnossus”; this interpretation supports the theory linking the Gnossiennes to the myth of Theseus, Ariadne and the Minotaur. Several archeological sites relating to that theme were famously excavated around the time that Satie composed the Gnossiennes.

However, I prefer the Dictionary of Obscure Sorrows’ definition:

gnossienne
n. a moment of awareness that someone you’ve known for years still has a private and mysterious inner life, and somewhere in the hallways of their personality is a door locked from the inside, a stairway leading to a wing of the house that you’ve never fully explored—an unfinished attic that will remain maddeningly unknowable to you, because ultimately neither of you has a map, or a master key, or any way of knowing exactly where you stand.

In 1891 Satie published Le Fils des étoiles (The Son of the Stars) for Joséphin Péladan’s Rosicrucian play of the same name, which includes what many consider the 7th Gnossienne despite its different tone and subject matter.