This interesting surname is of northern habitational origin deriving from the Old English pre 7th Century "grene" meaning green plus the Old Norse "saetr" a mountain pasture; hence "green pasture on a mountain". The surname would either be topographical for a "dweller by the green mountain pasture" or locational as a corrupted form of one of the many places called Greenside, e.g. in Durham, Westmorland, Huddersfield, etc.. The surname is first recorded in the early half of the 17th Century, (see below). In the modern idiom the surname has many variant spellings including Greensit, Greensite, Greenset, Greensett, etc.. On November 10th 1633, the marriage of John Greensett and Marie Simson took place at Chester le Street, Durham. William, son of William Greensitt, was christened on April 22nd 1707, at the same place. The christening of Lambton, son of Thomas and Elizabeth Greensitt, took place on July 10th 1768, at Bishopwearmouth, Durham. On March 4th 1769, Robert Greensitt married Jane Watson at St. Nicholas, Durham. The first recorded spelling of the family name is shown to be that of Thomas Greensett, witness at christening, which was dated January 14th 1633, in Chester le Street, Durham, during the reign of King Charles 1, knwn as "The Martyr", 1625 - 1649. 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.