infrequency
— Noun
– English
~ noteworthy scarcity
infrequent
— Adjective
– English
~ not frequent; not occurring regularly or at short intervals; "infrequent outbursts of temper"
infrequently
— Adverb
– English
~ not many times; "in your 1850 church you not infrequently find a dramatic contrast between the sumptuous appointments of the building itself and the inhuman barrack-like living conditions in the church room"