What term is defined as a person's expertise in a particular trade or technique?

The term that refers to a person's expertise in a particular trade or technique is skill. Skills are typically developed through practice and experience, and they can encompass a range of abilities specific to a profession or activity. For instance, a carpenter possesses skills in woodworking techniques, while a musician has skills in playing an instrument.

In contrast, ability generally refers to the capacity to perform tasks, which may or may not involve specialized training or experience. Talent implies a natural aptitude or proficiency in a specific area, which may not necessarily result from extensive training. Knowledge consists of the understanding and information acquired through education or experience, but it does not entail the practical application or demonstration of that information in a trade or technique. Thus, skill is the most appropriate term that encapsulates a person's hands-on expertise in a given field.