Proficiency is a good working command of a skill. Language proficiency, a proficiency test, demonstrate proficiency.
It sits below mastery and above competence, and it is the level at which somebody can actually use the skill for real work. In language teaching, proficiency is measured against defined levels rather than against a course.
1nounproficiencyA good working command of a skill.
“Applicants must show proficiency in English and one other language.”
proficiency is a skill.
Latin proficiens means making progress, from pro-, forward, plus facere, to make.
From proficient or its etymon, Latin prōficiēns, ency.
Etymology from Wiktionary, CC BY-SA