The root symbol is also known as the radical symbol or radix. It is the symbol for the square root of a number or its higher-order root. In advanced math, it has other meanings like radical of the ideal. There is no certain knowledge of when the root sign was used for the first time. Some historians speculate that it was used for the first time by Arab mathematicians in the 15th century.

Other scholars believe that it originated from the Latin letter r, which is the first letter in the word radix (means root) referring to the same mathematical operation.