- the symbol √ or indicating extraction of a root of the quantity that follows it, as √25=5 or .
Origin of radical sign
First recorded in 1660–70
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- the symbol √ placed before a number or quantity to indicate the extraction of a root, esp a square root. The value of a higher root is indicated by a raised digit in front of the symbol, as in ³√