The Collaborative International Dictionary
Tribasic
Tribasic \Tri*ba"sic\, a. [Pref. tri- + basic.] (Chem.) Capable of neutralizing three molecules of a monacid base, or their equivalent; having three hydrogen atoms capable of replacement by basic elements on radicals; -- said of certain acids; thus, citric acid is a tribasic acid.
Wiktionary
tribasic
a. 1 (context chemistry of an acid English) containing three replaceable hydrogen atoms 2 (context chemistry of a salt English) having three atoms of a univalent metal