A connoisseur is a person who, through study and interest, has a fine appreciation for something, like the connoisseur who can identify the clarinet player on a jazz recording by the sound of his inhalations alone.
A connoisseur is an authority in his field, someone who has expert knowledge and training, especially in the arts. A connoisseur may also be someone with an extremely developed sense of taste, like the connoisseur who can identify rare wine by a flavor others can't even detect. Then again, some people call themselves connoisseurs of just about anything they like — pizza, old vinyl albums, even cartoons — because they know so much about it.
