Parsippany-Troy Hills Township, commonly called simply Parsippany, is a township in Morris County, New Jersey, United States. As of the 2010 United States Census, the township's population was 53,238, reflecting an increase of 2,589 from the 50,649 counted in the 2000 Census, which had in turn increased by 2,171 from the 48,478 counted in the 1990 Census.The name Parsippany comes from the Lenape Native American sub-tribe, which comes from the word parsipanong, which means "the place where the river winds through the valley". Parsippany-Troy Hills is the most populous municipality in Morris County. The name Troy Hills was changed from Troy, to avoid confusion of mail being sent erroneously to Troy, New York.