Other forms: coexisting; coexisted; coexists
To coexist is to live in the same place or at the same time. If you, your roommate, and a cat all live in an apartment together, you can say the three of you coexist.
You can use the verb coexist to simply mean "exist together," or it can mean something more specific — to live peacefully or tolerantly in the same place. Two countries might have to work to find a way to coexist despite years of conflict, for example. The word has been around since the 1600's, but it wasn't used in this second, diplomatic way until 1931. Coexist combines exist, "be" or "live," with the prefix co, "together."