protactinium: Meaning and Definition of

prot•ac•tin•i•um

Pronunciation: (prō"tak-tin'ē-um), [key]
— n. Chem.
  1. a radioactive, metallic element. Symbol: Pa; at. no.: 91.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
See also: