proficiency
n.a high level of skill or knowledge in a particular subject or activity. You have this when you can do something very well, like speaking a language or using a computer.
n.a high degree of competence or expertise in a specific skill or field of knowledge. Often refers to the mastery of a language or technical ability.
“She has a high level of proficiency in English.”
“The job description requires candidates to demonstrate proficiency in at least two programming languages.”
“While basic communication is achievable within months, true linguistic proficiency requires years of immersion and a deep understanding of cultural nuances that go beyond mere grammar.”
Frequently followed by the preposition 'in' to specify the field of expertise.
Proficiency is almost always paired with the preposition 'in' rather than 'of' when describing a skill.
“Within the past 10 years, many schools have invested in evidence-based reading instruction , with a renewed emphasis in phonics instruction to improve students’ reading proficiency.”
“The pattern remained after we accounted for health status, English proficiency, financial hardship, education, employment, insurance coverage and time in the U.S.”
From proficient or its etymon, Latin prōficiēns (present participle of prōficiō), + -ency.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.