ˌkɒnə’sə:
■ noun an expert judge in matters of taste.

connoisseurship noun

C18: from obs. Fr., from conoistre ‘know’.
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Concise Oxford Thesaurus
connoisseur
▶ noun EXPERT, authority, specialist, pundit, savant; arbiter of taste, aesthete; gourmet, epicure, gastronome; informal buff; N. Amer. informal maven.
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Merriam-Webster Collegiate® Dictionary
con·nois·seur
Pronunciation: ˌkä-nə-‘sər also -‘su̇r
Function: noun
Etymology: obsolete French (now connaisseur), from Old French connoisseor, from connoistre to know, from Latin cognoscere ― more at COGNITION
Date: 1714

1 : EXPERT especially : one who understands the details, technique, or principles of an art and is competent to act as a critical judge
2 : one who enjoys with discrimination and appreciation of subtleties
–con·nois·seur·ship \-ˌship\ noun