Con`nois*seur" [F. connaisseur, formerly connoisseur, fr. connaitre to know, fr. L. cognoscere to become acquainted with; co- + noscere, gnoscere, to learn to know. See Know, amd cf. Cognizor.]
One well versed in any subject; a skillful or knowing person; a critical judge of any art, particulary of one of the fine arts.
The connoisseur is "one who knows," as opposed to the dilettant, who only "thinks he knows."
© Webster 1913.