The Collaborative International Dictionary
niobic acid
Columbic \Co*lum"bic\, a. [From Columbium.] (Chem.) Pertaining to, or containing, columbium or niobium; niobic.
Columbic acid (Chem.), a weak acid derived from columbic or niobic oxide, Nb2O5; -- called also niobic acid.
Wiktionary
niobic acid
n. (context chemistry English) the hypothetical acid HNbO3 derived from niobic oxide Nb2O5, only known as its salts, the niobates