Pronunciation: (pu-tas'ē-um), [key]
a silvery-white metallic element that oxidizes rapidly in the air and whose compounds are used as fertilizer and in special hard glasses. Symbol: K; at. wt.: 39.102; at. no.: 19; sp. gr.: 0.86 at 20°C.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.