What is mastery

In the pursuit of continuing education and personal growth, I frequently come across classes and seminars with titles such as "A Master Class in Skill X" or "Master the Art of Skill Y." For some reason, the term "master" does not sit well with me.  

​Oxford Languages defines the verb master as follows:

1. 1. acquire complete knowledge or skill in (an accomplishment, technique, or art).  "I never mastered Latin."
2. 2. gain control of; overcome.  "I managed to master my fears."

Based on these definitions, when you master a skill, you're done; there is no further room for growth. I do not feel that we can ever master soft skills like communication or leadership. Over time, we can improve even applied skills, such as writing code or creating a physical product. We can become extremely proficient, but there is always room to grow. Because the world around us does not remain static, we must continually adapt how we apply our skills.  

The adjective master means having or showing very great skill or proficiency. "An emotional performance from a master pianist."  I can accept this definition, but I would prefer to use the term proficient or highly skilled.  

It feels insincere to claim that someone will master a skill by taking a class or seminar. Proficiency happens over time. Even people at elite levels will tell you they still strive to improve. Continuous improvement should be the goal, not mastery.  

​What are your thoughts? Do you have a different response to the term master? How would you re-brand a master class?