1. (noun)hafnium, Hf, atomic number 72 a grey tetravalent metallic element that resembles zirconium chemically and is found in zirconium minerals; used in filaments for its ready emission of electrons Synonyms: hafnium, atomic number 72, highfrequency
2. (noun)high frequency, HF 3 to 30 megahertz Synonyms: highpitch, high frequency, atomic number 72, hafnium