CatalystA catalyst is an event or person causing a change. Getting kicked out of your parents' house might be a catalyst for becoming more independent.
The noun catalyst is something or someone that causes a change and is derived from a Greek word. It can be somewhat ordinary, like a hot day being a catalyst for getting your hair cut really short. Or it can be major, like how the assassination of the archduke Franz Ferdinand of the Austro-Hungarian Empire is said to be a catalyst of World War I.
Synonyms1. impetus incentive motivation stimulant
Antonyms1. block