Pronunciation: (kat'l-ist),[key] —n. 1. Chem.a substance that causes or accelerates a chemical reaction without itself being affected.
2. something that causes activity between two or more persons or forces without itself being affected.
3. a person or thing that precipitates an event or change: His imprisonment by the government served as the catalyst that helped transform social unrest into revolution. 4. a person whose talk, enthusiasm, or energy causes others to be more friendly, enthusiastic, or energetic.