(しろうと) An amateur as opposed to a professional. An every-day, untrained person, as opposed to a specialist. Can also be used to describe someone who has never done xxx.
(しょしんしゃ) A beginner at something – beginner driver, a noob.
(みじゅく) Someone who has really sloppy or clumsy, poor technique at something – who does it LIKE a beginner, even if they’ve been doing it for years.