-something that causes activity between two or more persons or forces without itself being affected.
-a person whose talk, enthusiasm, or energy causes others to be more friendly, enthusiastic,or energetic.
A person or thing that creates change, but does not change itself. That is probably the easiest way to put it. If you think about it, that is what Christ calls us to be. We are supposed to be catalysts for Him, a person that changes others but does not change ourselves. As you go through this week, think about how you can be a catalyst in someone else's life. Don't let them change you, influence them and change them for the better!