Answer: nullset

AnswerCrossword Clue
NULLSETGroup with no members, in math
NULLSETMathematical void
NULLSETIt has no members, in math
NULLSETIntersection of perfect squares and prime numbers
NULLSETIt's empty
NULLSETIt has zero measure, in math
NULLSETThere's nothing to it
NULLSETIt's got nothing