the colourless aqueous solution of hydrogen fluoride: a strong acid that attacks glass
hydrofluoric acid in American English
(ˌhaɪdroʊˈflɔrɪk; ˌhaɪdroʊˈflʊrɪk)
a strong, fuming acid that is a water solution of the gas, or liquid, hydrogen fluoride (H6F6, H4F4, H2F2, or HF, depending on the temperature): it reacts with silicates and is therefore used in etching glass