What makes a change happen faster without being consumed by it. A catalyst enables and is not spent.
Greek katalysis (a dissolving, a breaking up), from katalyein (kata- down + lyein, to loosen); adopted into English chemistry in the 19th century for a substance that speeds a reaction without being consumed by it, and later generalized.
What makes a change happen faster without being used up by it — a catalyst enables and is never itself spent.