The sign $\sqrt{}$ used in connection with square roots, cube roots, and, more generally, nth roots for larger values of n. The notation $\sqrt{a}$ indicates square root, $\sqrt[3]{a}$ indicates cube root and $\sqrt[n]{a}$ indicates nth root of a. For a detailed explanation of the correct usage of the notation, see nth root, square root. See also solvable by radicals.