tetracid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Capable of reacting with four molecules of a monobasic acid. Used of a base.
• adjective Containing four replaceable hydrogen atoms. Used of an acid or acid salt.
• noun An acid containing four replaceable hydrogen atoms.

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

• adjective (Chem.) Capable of neutralizing four molecules of a monobasic acid; having four hydrogen atoms capable of replacement ba acids or acid atoms; -- said of certain bases.

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

• adjective obsolete, chemistry tetrabasic