Definition of "expertness" [ex•pert•ness]

• The state of being expert; skill or proficiency (noun)

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• "Regarding the subject at hand here, though, I think that "expertness" in the case of the violinist and the programmer, it had a lot to do with being an expert at the use of the very few tools for those 10,000 hours (violin + sheet music or computer and programming language)."
• "I was ASTOUNDED by Mexico's intelligence and expertness in response and preparation for the cane."
• "Paraprofessional aides are much less technically expert than are professionals, but they often more than make up for their lower degree of technical expertise through their greater social expertness."