1. To focus on someone or something. A noun or pronoun can be used between "center" and "on." But it's Beth's surprise party, not yours, so all the decorations and games should center on her and her alone. This novel centers on the protagonist's journey to self-discovery.

2. To position something in the center of a space, usually a wall. A noun or pronoun can be used between "center" and "on." That picture just isn't centered on the wall—tilt it a little more to the left.

1. Not perfectly lined up in the center of something. I don't know. I still think the picture looks a little off-center.

2. Not standard, typical, or usual; unique or odd. We've taken an off-center approach to solving this problem.