Noah Webster's Dictionary (n.) The quality of being proficient in the acquisition of any art, science, or knowledge; progression in knowledge; improvement; adeptness; as, to acquire proficiency in music.

Multi-Version Concordance Proficiency (1 Occurrence) 1 Timothy 4:15 Habitually practise these duties, and be absorbed in them; so that your growing proficiency in them may be evident to all. (WEY)