Someone (usually a female) who is both incredibly adept and experianced in the art of fellatio. To be a true Dome doctor, the sujbect in question must be so good at giving blow jobs that they might have gone through several years of college to earn a degree in the skill. Only the very best cocksuckers get this coveted title.
Damn Jeanne-Marie, when it comes to sucking cock, you're one hell of a Dome Doctor!