Infrequency :: Infrequency (n.) The state of rarely occuring; uncommonness; rareness; as, the infrquence of his visits..
Infrequency :: Infrequency (n.) The state of not being frequented; solitude; isolation; retirement; seclusion.
Infrequent :: Infrequent (a.) Seldom happening or occurring; rare; uncommon; unusual.