tremendously low frequency

The term tremendously low frequency (TLF) is likely an Internet misnomer that won't die, presumed to mean electromagnetic radiation (EMR) with a frequency below 3 Hz. One can use the term, but it appears to be some individual's invention suggested by ITU band names; ITU has "THF" beyond "EHF" (extremely high frequency) and has "ELF" for the 3-30 MHz, thus the name TLF suggests itself for an adjacent lower-frequency band. However the ITU does not use the term TLF and specifies no band name for frequencies below 3 Hz.

I initially wrote this page based upon Wikipedia's listing of TLF, but since then, TLF was removed from Wikipedia, undoubtedly by someone adjusting it to reflect ITU-defined band names. Later Wikipedia and other sites have referred to this page (that you are reading) when they mention the term.

These frequencies fall within ranges often classified as subradio. Searching online, I've found names (by bodies other than ITU: other bodies do define bands for their own specialties and/or localities) for some narrower defined bands falling within the range but no name specifically for 0-3 Hz.