This surname ARNOLDY was from a Norman personal name composed of the elements 'arn' (eagle) and 'wald' (rule). The earliest French hereditary surnames are found in the 12th century, at more or less the same time as they arose in England, but they are by no means common before the 13th century, and it was not until the 15th century that they stabilized to any great extent; before then a surname might be handed down for two or three generations, but then abandoned in favour of another. In the south, many French surnames have come in from Italy over the centuries, and in Northern France, Germanic influence can often be detected. The name was taken early to England by settlers and there were places of the name, a village in the parish of Riston, County York, and a parish in County Nottingham from where the name may have been derived. Early records of the name mention Ernold Rogerus filius Ernaldi who was listed as a tenant in the Domesday Book of 1086. Stephen Arnold of the County of Kent was recorded in the year 1273. Ayelina relicta Arnold of the County of Huntingdonshire in 1273. Walter Arnald was the rector or Thelton, County Norfolk in 1409. Warin Arnold of Norwich was recorded in 1486. John Arnold and Winifred Nelham were married in London in 1611. Richard Jaggard and Eedy Arnald were married at St. Antholin, London in 1616. The earliest hereditary surnames in England are found shortly after the Norman Conquest of 1066 and are of Norman French origin rather than native English. On the arrival of the Normans they identified themselves by references to the estates from which they came from in northern France. These names moved rapidly on with their bearers into Scotland and Ireland. Others of the Norman Invaders took names from the estates in England which they had newly acquired.Thomas Arnold (1795-1842) was the Headmaster of Rugby, which he raised to the rank of a great public school. Matthew Arnold (1822-1888) was an English poet and critic of distinction, and the son of Thomas.

The associated coat of arms is recorded in Riestaps Armorial General.