/kat"l ist/ , 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.
[ 1900-05; CATALY(SIS) + (-I)ST ]