Sentence:  When he had gazed at the stars sufficiently as they shone over his mistress's window, and put her candle to bed, re repaired to his own dormitory, and there, no doubt, thought of his Maria andhis horse with youthful satisfaction, and how sweet it would be to have one <WSD>pillioned</WSD> on the other, and to make the tour of all the island on such an animal with such a pair of white arms round his waist. 
Meaning of the word marked with <WSD> tags:  To ride on a pillion.