What word describes someone who is very skilled and competent in a certain area?

The term "proficient" specifically refers to someone who has a high degree of skill and competence in a particular area. This word is often used to describe individuals who have acquired a significant level of expertise through knowledge and practice. For example, a proficient musician expertly performs their instrument, and a proficient writer adeptly crafts complex narratives.

In contrast, the other options do not accurately convey the same meaning. "Validated" refers to confirming the truth or accuracy of something, which does not relate to skill level. "Inexperienced" signifies a lack of experience, which is the opposite of being skilled. Lastly, while "confident" implies a sense of self-assurance, it does not necessarily indicate competency or skill. Therefore, "proficient" is the most appropriate choice for describing someone who is highly skilled and competent in a specific area.