Polyp: tissue growth on one or both of the vocal folds that could be compared to a blister because of its soft texture filled with fluid.  Tobacco use  is most often associated with the occurrence of a polyp although once again voice overuse can generate it.  

Click on the links below for video examples:
http://www.entusa.com/vocal_cord_polyp_2.htm
http://www.entusa.com/vocal_cord_polyp_4.htm