A muso is a person who is obsessed with music.

Their record collection will contain music and artists nobody else has heard of, and if they believe that an artist is becoming popular they will deny they ever listened to them and quickly dispose of any evidence.

If they come around to your house they will make a beeline for your music collection and then criticise everything in it just to make sure you know they are cool.

As a sideline they will take up the acoustic guitar and then force you to listen to their "revolutionary" take on what music could be like. It will undoubtedly be dreadful and unlistenable.
You're such a muso, if other people have heard of it you hate it.
by Squishflop December 27, 2010
Muso is a derogatory term for musicians, typically used by sound engineers.
"Fucking Musos showed up late, missed the sound check and then tried to tell me I wasn't mixing the bass loud enough."
by BurbanIctionary June 28, 2014
A cruise ship musician who sleeps all day plays half the night and spends the other half trying to fuck a dancer.
That fuckin Muso is still sleeping?
by Soundtaudio May 25, 2014
A Musical Theatre student or someone who is obsessed with musicals and likes to sing all the time.
*Hears group singing a song from 'Wicked'* Oh god they are such a muso.
by generalannoyance May 24, 2011
Someone who is obsessed with listening to and creating music. Most can play mope than one instrument, and do so at any opportunity.
guy1: Look at this guy! He plays guitar, piano, AND has professional singing lessons!
guy2: Yeah, he's a real muso.
by Bob November 13, 2003
A musician who uses 12 chords where 3 will suffice.
Why do Rush have to include so many deeply unnecessary chord changes in their songs? Man, what a bunch of total musos.
by Mysterious Alan December 24, 2006
muso - (moozoe) is a derogatory word short for muslim.
by Mohammed Ahmed Muso January 22, 2018