biacid

from The Century Dictionary.

• In chem., capable of combining with an acid in two different proportions: said of a base.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Chem.) Having two hydrogen atoms which can be replaced by negative atoms or radicals to form salts; -- said of bases. See diacid.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective chemistry Having two hydrogen atoms that can be replaced by negative atoms or radicals to form salts.