noun
expertise
ek-spur-TEEZ/ˌekspɜːrˈtiːz/
Specialized knowledge or skill in a particular field.
The craftsperson's expertise shows in the precise violin repair.

Etymology
Built on expert, meaning “experienced” or “skilled,” French expertise named an expert appraisal or report. In English, it names the specialized skill or knowledge itself.
In context
The author is not an herbalist or pharmarmacologist, so is not claiming that his suggestions in using herbs are based on any specialized expertise on his part.
More examples
- She brought valuable legal expertise to the team.
- We relied on his expertise in restoring old furniture.
- The project was outside my area of expertise.
Forms
expertise
expert noun — a person with specialized knowledge or skill
Similar words
- skill
- Can be practical ability without extensive specialized knowledge.
- proficiency
- Emphasizes competent performance in a task.