extremely low frequency extremely high frequency • extremeness · · · Info · Definitions · Synonyms · Characters · · extremely low frequency · · Text Common · · Latin · · Scripts 23 · · Length 8 · · Syllables Definitions · · · (noun) below 3 kilohertz. Synonyms: extremely low frequency, ELF. · · Noun Definition 1 Synonyms · · · elf · · Synonym 1 Characters · · space U+0020 c latin small letter c U+0063 e latin small letter e U+0065 f latin small letter f U+0066 l latin small letter l U+006C m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F q latin small letter q U+0071 r latin small letter r U+0072 t latin small letter t U+0074 u latin small letter u U+0075 w latin small letter w U+0077 x latin small letter x U+0078 y latin small letter y U+0079