amphoteric (adj.)

of a chemical compound, "capable of reacting either as an acid or as a base," 1832, from Greek amphoteros "each or both of two," a variant of ampho "both" that replaced the earlier word. It is identical with Latin ambo and ultimately from the source of amphi- (q.v.). Other languages have the word without the nasal (Old Church Slavonic oba, Lithuanian abu) and Germanic has it without the initial vowel (Gothic bai). De Vaan writes, "There is no overall explanation for the forms, but connection with [amphi] seems clear."