This most interesting surname is of Old Gaelic origin, and is a contracted form of Mac Cashin, the Anglicized form of the Gaelic "Mac Caisin", which is composed of the Gaelic prefix "Mac", son of, and a byname "Caisin", from "cas", meaning crooked or curly (headed). The MacCashins were hereditary physicians in Upper Ossory, now the county of Kilkenny, and some adjacent areas. The surname first appears in the late 13th Century (see below), while as early as 1304 it is found in nearby Kildare, and in 1331 in north Tipperary. Bishop John O'Cassin resigned the see of Killala in 1490. The Hearth Money Rolls of 1666 indicate that MacCashin was then a popular name in County Tipperary. The most well known of the aforesaid physicians was Conly Cashin, who wrote a medical tract in Latin in 1667. At the end of the 18th Century there was a notable firm of shipowners in Waterford, "Cashin, Wyse and Quan". Daniel Cashin, aged 21 yrs., a labourer, was a famine emigrant who embarked from Liverpool aboard the "Commerce" on May 20th 1847, bound for New York. Variants of the surname include Cashen, Casheon, Cashion, Cashon, Cassin and Cassion. The first recorded spelling of the family name is shown to be that of Kenedi carach O'Cassin, which was dated 1295, in the "Judiciary Rolls", Ireland, during the reign of King Edward 1 of England, known as "The Hammer of the Scots", Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.1272 - 1307.