The Sir name Day is said to have Irish and English origins. According to the Irish origin a family with this name was fist found in County clare and the name was derived from the word ‘O Deaghaidh’. According to the English origin the name has various sources like it was a name for dairy maids, at times it was derived from David and else where it was derived from the word ‘d’eye’ which means eye. The family was first found in Somerset in England.