A multiplicative character is called unitary if it has absolute value 1 everywhere.
Unitary Multiplicative Character
See also
Multiplicative CharacterExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Unitary Multiplicative Character." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/UnitaryMultiplicativeCharacter.html