Sentence:  "It was a purely scientific research party sent out by my father's father, the Jeddak of Helium, to rechart the air currents, and to take atmospheric density tests," replied the <WSD>fair</WSD> prisoner, in a low, well-modulated voice. 
Meaning of the word marked with <WSD> tags:  Beautiful, of a pleasing appearance, with a pure and fresh quality.