relative frequency, absolute frequency, oftenness, frequence, amplitude, freq, intensity, infrequency, wavelength, regularity, more...

rarity, infrequency, seldomness, scarcity, uncommonness

radio frequency, microwave frequency, infrared frequency, X-ray frequency, gammray frequency, more...

high, low, relative, natural, same, resonant, fundamental, greater, spatial, single, angular

how often,   how many times,   number of times,   wavelength measure,   how common,   amount of times,   the amount of times,   how common it is,   common ness,   radio band