Addend

A quantity to be Added to another, also called a Summand. For example, in the expression $a+b+c$, $a$, $b$, and $c$ are all addends. The first of several addends, or ``the one to which the others are added'' ($a$ in the previous example), is sometimes called the Augend.

See also Addition, Augend, Plus, Radicand