Sentence:  It is natural from the marksman 's viewpoint to call a bull's-eye a success , but in the <WSD>mice</WSD> example it is arbitrary which category corresponds to straight hair in a mouse . 
Meaning of the word marked with <WSD> tags:  any of numerous small rodents typically resembling diminutive rats having pointed snouts and small ears on elongated bodies with slender usually hairless tails