This name is of Northern English locational origin from any of the places thus called for example, Thornthwaite in Cumberland, Westmoreland and the West Riding of Yorkshire. Recorded respectively as Thornthwayt, Thornthwait and Tornhweit in the 13th Century Pipe Rolls of the various counties, the name in all cases derives from the Olde English pre 7th Century "thwaite", itself coming from the Olde Norse "thveit" meaning a meadow or piece of land, plus the Olde English "thorn", a thorn bush hence, "land on which thorn bushes grew". On October 11th 1789 Margaret, daughter of Thomas and Elizabeth Thornthwaite was christened in Hutton Magna, Yorkshire and on November 5th 1836 Ann Hay Thornthwaite and Isaac Bradley were married in Kirkby Lonsdale, Westmoreland. The first recorded spelling of the family name is shown to be that of Thomas Thornewhaite married Mabell Fary, which was dated December 15th 1588 in Dalston, Cumberland, during the reign of Queen Elizabeth I, Good Queen Bess, 1558 - 1603. 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.