| Word | Definitions | Synonyms |
|---|---|---|
| addend | (noun) a number that is added to another number (the augend) | - |
| addendum | (noun) textual matter that is added onto a publication; usually at the end | Synonyms: postscript, supplement |
| adder | (noun) small terrestrial viper common in northern Eurasia | Synonyms: common viper, Vipera berus |
| (noun) a machine that adds numbers | - | |
| (noun) a person who adds numbers | - |