Data, security, network

The twenty-fifth entry is o algoritmo, and it carries a man’s name that neither language spells any more. Al-Khwārizmī was a mathematician in ninth-century Baghdad, and the book he wrote brought the Indian numerals and the rules for calculating with them into Arabic. Medieval Latin attached his name to the method itself, and from there it travelled on. Portuguese received it twice, by two separate roads. One of them gave o algoritmo, the ordered list of steps that this entry is about. The other gave o algarismo, which is not a procedure at all but a single digit: um número de quatro algarismos is a four-figure number, and every child meets the word long before meeting any mathematics. English kept only the first of the two. For the digit it went to Latin instead and took « digit », from digitus, a finger, because fingers are what people counted on before the numerals arrived. So one man stands behind a Portuguese word for the schoolroom and an English word for the computer, while behind « digit » there is nobody at all, only a hand.