skilled, proficient, knowledgeable, well-informed, expert, adept, experienced, practised, accomplished, well-versed
perfected - honed - polished - refined - excelled at - fully learned - fully understood - become proficient in - become adept at - conquered - nailed - aced
“Mastered” describes a state in which someone has achieved full control, comprehensive understanding, or very high proficiency in a particular subject, activity, or skill. It implies that the person can perform reliably and confidently, often without needing guidance or support. The term can apply to academic topics, practical crafts, artistic abilities, languages, or professional techniques. When something is mastered, errors are rare and challenges in that area are handled with ease and flexibility. It often follows a period of practice, study, or training, and suggests that the learner has progressed from basic competence to an advanced, expert level.