definition of square rooting
square root. (MATHEMATICS) each positive number has another number that, when multiplied times itself, equals that number. So, for example, 4 has a square root of 2 (2 x 2 = 4). The square root of a negative number is an imaginary number. Imaginary numbers are not, by themselves, useful solutions to math problems; but they can be used to find them. BILL: Anna, we have a rectangle that's 3 x as long as it is wide, and it encloses an area of 300 square meters.