Musician? Ha! (Noun) Refers to someone with absolutely no musical talent who nevertheless pretends to be a musician. Should be said with a loud, indignant guffaw. 

Scarlett Johansson. Musician? Ha! Record all the shitty albums you want, go on a goddamn World Tour, carry a guitar, and flaunt your cleavage in every motherfucking music magazine in publication, you will never be any more of a musician than Lindsay Lohan or Paris Hilton. You're just a fucking album cover. That's it.