He's '(as) stubborn as a mule'. [=he's very/extremely stubborn]
She 'has a stubborn streak'. [=she is often stubborn]
She's wrong, but she's too 'stubborn' to admit it.
(..) I'm too extraordinary to clean. But... You've been an excellent example to me, Dr. Brennan. Be confident, be stubborn, and shout down the opposition, eh? Well, I... I must go now. And you're welcome (..)2014 TvShow: Bones Title: The Master in the Slop Season: 9 Episode 14