lanthanum Hear it!

lanthanum definition

lan·tha·num (-nəm)

noun

a soft, malleable, silvery chemical element, one of the rare-earth elements and the first member of the lanthanide series: symbol, La; at. no., 57

Etymology: ModL: so named (1839) by G. Mosander (see erbium) < lanthana, lanthanum oxide, lit., the hidden one < Gr lanthanein, to be hidden (see latent): it had previously been undetected in the mineral cerite

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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