adder addendum • adderbolt · · · Info · Definitions · Synonyms · Characters · · adder · · Text Latin · · Script 5 · · Length Definitions · · · (noun) a person who adds numbers. · · Noun Definition 1 (noun) a machine that adds numbers. · · Noun Definition 2 (noun) small terrestrial viper common in northern Eurasia. Synonyms: common viper, Vipera berus. · · Noun Definition 3 Synonyms · · · common viper · · Synonym 1 vipera berus · · Synonym 2 Characters · · a latin small letter a U+0061 d latin small letter d U+0064 e latin small letter e U+0065 r latin small letter r U+0072