1. to do together
一緒にしたいこと、いっぱいあるだろ？There are lots of things we want to do together, right?
2. to put together; to lump together; to mix; to join
だから、寝室を一緒にしたらどうかと言っているんです！！So I'm saying, why not share one bedroom?!
3. to regard in the same light; to put in the same category; to class ... with ...; to confuse
あたしをあんな奴と一緒にしないでよ。Don't lump me in with someone like that.
4. to arrange for (two people) to marry