amphoteric

adj. functioning as both an acid and a base (Chemistry)

In chemistry, an amphoteric substance is one that can react as either an acid or base.
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Adjective
1. having characteristics of both an acid and a base and capable of reacting as either
(synonym) amphiprotic
(antonym) acidic
(classification) chemistry, chemical science

(a.)
Partly one and partly the other; neither acid nor alkaline; neutral.
  

 Say it 
A substance that can act as either an acid or a base in a reaction. For example, aluminum hydroxide can neutralize mineral acids ( Al(OH)3 + 3 HCl = AlCl3 + 3 H2O ) or strong bases ( Al(OH)3 + 3 NaOH = Na3AlO3 + 3 H2O).