a person or thing without an equal

Pronunciation:
NUN-such

In a sentence:
Brett was viewed as a nonesuch amongst his medical school peers; but his close friends knew that he was just an attractive poser who was having an affair with the dean.

In a different sentence:
In the sport of glove-less boxing, Ricky was a nonesuch and an idol; he was four-foot-four, bald, and did one thousand push-ups a day using only his knuckles.