AX / SAX / TUBAX

musical instruments

AX, or axe, is slang for any musical instrument. (I first heard the term used in this way by jazz musicians,* but rock guitarists like it too!)
SAX is short for saxophone, which refers to a broad range of instruments.
The TUBAX was designed—but never built—by Adolph Sax, the creator the saxophone and saxhorn families.

*Other esoteric lingo I learned playing jazz include saying "chart" to mean "piece of music," "book" to mean "repertoire," and "gig" to mean "job," e.g. "My favorite chart in our book to play at any gig is 'It Don't Mean A Thing.'"