principal root

principal root (plural principal roots)

1. (mathematics) A real number, preferably a nonnegative one if such a root exists, which when raised to the power of n is equal to the radicand of its nth degree radical.

   The square roots of 4 are 2 and -2, the principal square root of 4 is 2.

   The real 4th roots of 16 are 2 and -2, the principal 4th root of 16 is 2.

   The real cube root of -27, also its principal cube root, is -3.

Unless specified otherwise, the principal root is often implied when talking about roots.

• principal square root
• absolute value
• root
• √