A substance whose presence alters the rate at which a chemical reaction proceeds, but whose own composition remains unchanged by the reaction. Catalysts are usually employed to accelerate reactions(positive catalyst), but retarding (negative) catalysts are also used.
(Source: ALL)
A substance which speeds up chemical reactions.
something that causes an important event to happen; "the invasion acted as a catalyst to unite the country"
(chemistry) a substance that initiates or accelerates a chemical reaction without itself being affected
something that causes an important event to happen
