|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|an extraordinary or unusual thing, person, or event; an exceptional example or instance.|
catalysis ca·tal·y·sis (kə-tāl'ĭ-sĭs)
n. pl. ca·tal·y·ses (-sēz')
The action of a catalyst, especially an increase in the rate of a chemical reaction.
|catalyst (kāt'l-ĭst) Pronunciation Key
A substance that starts or speeds up a chemical reaction while undergoing no permanent change itself. The enzymes in saliva, for example, are catalysts in digestion.
catalytic adjective (kāt'l-ĭt'ĭk)