adder2Pronunciation: /ˈadə(r)/Entry from World dictionaryTranslate adder | into French | into German | into Italian | into Spanish Definition of adder noun Electronics a unit which adds together two input variables. A full adder can add a bit carried from another addition as well as the two inputs, whereas a half adder can only add the inputs together. adder in other Oxford dictionaries Definition of adder in the British & World English dictionary