Definition:Matrix/Order

Definition
Let $\sqbrk a_{m n}$ be an $m \times n$ matrix.

Then the parameters $m$ and $n$ are known as the order of the matrix.

Also known as
The order of a matrix can also be referred to as its dimensions, but the term dimension has a different, deeper meaning in linear algebra and this may be a source of confusion.

Some sources refer to the size rather than order, which is acceptable enough.