You must be an Oxford man, carrust. They use the word "nerd" (OU Dictionary) for that little saddle fetish.
We happened to land on that word in 2nd year at Uni for two folk who had failed first year courses and had to do a re-sit 1st year course in Philosophy or IT - we insisted they had to incorporate three words into their term papers, each chosen from the Chambers massive dictionary (50k words) when they were blindfolded. "Nerd (OU def)" being one of them and much to our considerable mirth too, it must be said. One of the other words was "horse" into an IT paper.....