subject matter expert

• subject matter experts have developed their expertise in their particular discipline over a long period of time and after a great deal of immersion in the topic.

Many subject matter experts have pursued advanced degrees in their area of specialization.Additionally, the experts maintain a rigorous program of continuous study in their field. Many are active as authors, publishing books or articles on their topic. Others serve as educators in college and universities.
"Mary is our expert on that particular operating system. She can help us assess whether this new application is compatible with others."
"Juan is our data management specialist. He helps us understand how to extract and format the data for our marketing project."
"Dave is the Chief Software Architect for our software company. He understands our customer needs and how our software products must be designed to meet those needs better than anyone in our firm."
https://www.thebalancecareers.com/subject-matter-expert-2275099