Which word is associated with someone who has a specialized skill or occupation?

The term "professional" is associated with someone who has a specialized skill or occupation because it denotes a level of expertise and formal training in a particular field. A professional typically adheres to established standards and ethics within their occupation and often has obtained relevant qualifications or certifications that recognize their competency. This word emphasizes not only the skill level of an individual but also the commitment to their profession, often implying that they earn a living through their specialized skills.

In contrast, the other terms suggest varying levels of experience or commitment. An "amateur" typically refers to someone who engages in an activity for enjoyment rather than as a profession, while a "novice" is someone who is new or inexperienced in a particular field. An "expert" indicates a high level of skill or knowledge, but it does not inherently carry the connotation of formal employment or adherence to professional standards that "professional" does.