Sentence:  ‘[…] There's every Staffordshire crime-piece ever made in this cabinet, and that's <WSD>unique</WSD>. The Van Hoyer Museum in New York hasn't that very rare second version of Maria Marten's Red Barn over there, nor the little Frederick George Manning—he was the criminal Dickens saw hanged on the roof of the gaol in Horsemonger Lane, by the way—' 
Meaning of the word marked with <WSD> tags:  Being the only one of its kind; unequaled, unparalleled or unmatched.