Synonyms for Proficiency:

n.

gift, prowess. knowledge, expertness, command, art. ability, skillfulness (noun)
dexterity, competence, aptitude, know-how, mastery, talent, expertness, skill, expertise, facility, knack, knowledge.
cognition (noun)
technique.
experience (noun)
practice, background, wisdom, sophistication, wit, savoir-faire.
knowledge (noun)
expertise.
method (noun)
technique.
proficiency (noun)
technique.
skill (noun)
craft, aptitude, adroitness, skill, talent, dexterity, competence, genius, acuity, mastery, artfulness, knack, deftness, technique, know-how, expertise, cunning, facility, adeptness, flair, ability, experience, capability.

v.

learning (verb)
knowledge.

Other synonyms:

prowess, knowledge, gift, expertness. art. Other relevant words:
command, art, knowledge, gift, prowess, expertness.

Usage examples for proficiency

  1. " The more serious events which gave my life this particular bias occurred in my twentieth year, when I had already left even the high school behind me; nor was I fully carried away by their influence till after my uncle had procured me several opportunities of proving my proficiency in my calling. – The Complete Historical Romances of Georg Ebers by Georg Ebers
  2. A host is presented as having invited to his table as many of his friends as were conspicuous for their proficiency in swearing. – A Cursory History of Swearing by Julian Sharman
  3. The proficiency of his elder sons and pupils, and his wife's talent as a singer, were a farther source of strength to the Society, whose direction undoubtedly made these years the happiest in Bach's life. – Johann Sebastian Bach by Johann Nikolaus Forkel and Charles Sanford Terry