to mix; to stir; to blend
to mix in (e.g. an ingredient)
砂糖と塩を混ぜないでください。
Please do not mix sugar and salt.
卵と牛乳をよく混ぜた方がいい。
You should mix the eggs and milk well.
砂糖と小麦粉を先に混ぜておくと楽だ。
It's easier if you mix the sugar and flour first.