Meaning

noun empty rhetoric or insincere or exaggerated talk

noun a genre of popular music that originated in New Orleans around 1900 and developed through increasingly complex styles

noun a style of dance music popular in the 1920s; similar to New Orleans jazz but played by large bands

originUnknown. First attested around 1912 in a discussion of baseball; attested in reference to music around 1915. Numerous references suggest that the term may be connected to jasm and jism.

Etymology from Wiktionary, CC BY-SA 3.0