periodicity

is likely misspelled.

has no English definition.

As a noun periodicity

is recurrence of a woman's periods; menstruation.

As nouns the difference between periodicity and aperiodicity

is that periodicity is recurrence of a woman's periods; menstruation while aperiodicity is the condition of being aperiodic.

In mathematics|lang=en terms the difference between periodicity and antiperiodicity

is that periodicity is (mathematics) the quality of a function with a repeated set of values at regular intervals while antiperiodicity is (mathematics) a generalization of periodicity such that f(x + p) = −f(x)'' for all ''x'' in some function ''f .

As nouns the difference between periodicity and antiperiodicity

is that periodicity is recurrence]] of a woman's [[period|periods; menstruation while antiperiodicity is (mathematics) a generalization of periodicity such that f(x + p) = −f(x)'' for all ''x'' in some function ''f .