Definition:Addition/Summand

Definition
Let $a + b$ denote the operation of addition on two objects.

The objects $a$ and $b$ are known as the summands of $a + b$.

Note that the nature of $a$ and $b$ has deliberately been left unspecified.

They could be, for example, numbers, matrices or more complex expressions constructed from such elements.

Also see

 * Use of this concept in the context of sum notation.