radical sign
noun Mathematics.
the symbol √ or 
indicating extraction of a root of the quantity that follows it, as √25=5 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
Words nearby radical sign
radical expression,
radical hysterectomy,
radical left,
radical mastectomy,
radical right,
radical sign,
radicalism,
radicalize,
radically,
radicand,
radicant
British Dictionary definitions for radical sign
radical sign
noun
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√