The result or act of joining together; a match or alignment; facing each other; also used for combining/totaling depending on context.
布の合わせを確認してから縫い始めてください。
Please check how the fabric pieces align before you start sewing.
二人の意見の合わせがうまくいかない。
The two people's opinions are not matching up well.
売上を合わせると、今月は目標を超えた。
Adding up the sales together, this month exceeded the target.
合わせの鏡を使うと無限に反射が続く。
When you use facing mirrors, reflections continue infinitely.