A catlyst is someone (or an event) that causes change.
A Catalyst makes a chemical reaction proceed faster, but is not used up by the reaction.
A catalyst is a substance that makes chemical reactions happen faster. They don't affect the outcome of the reaction, only the time in which it happens.
We became catalyst when we visit to in-laws home.
In chemistry it is called a catalyst. In biology it is called a enzyme. When a living organism produces a catalyst its called an enzyme.