lanthanum

[ lan-thuh-nuh m ]
/ ˈlæn θə nəm /

noun Chemistry.

a rare-earth, trivalent, metallic element, allied to aluminum, found in certain minerals, as monazite. Symbol: La; atomic weight: 138.91; atomic number: 57; specific gravity: 6.15 at 20°C.

Origin of lanthanum

< New Latin (1841), equivalent to lanthan- (< Greek lanthánein to escape notice; referring to its position on the periodic table) + -um, variant of -ium -ium
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Examples from the Web for lanthanum

British Dictionary definitions for lanthanum

lanthanum

/ (ˈlænθənəm) /

noun

a silvery-white ductile metallic element of the lanthanide series, occurring principally in bastnaesite and monazite: used in pyrophoric alloys, electronic devices, and in glass manufacture. Symbol: La; atomic no: 57; atomic wt: 138.9055; valency: 3; relative density: 6.145; melting pt: 918°C; boiling pt: 3464°C

Word Origin for lanthanum

C19: New Latin, from Greek lanthanein to lie unseen
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for lanthanum

lanthanum

[ lănthə-nəm ]

n. Symbol La

A soft malleable metallic rare-earth element used in glass manufacture. Atomic number 57.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for lanthanum

lanthanum

[ lănthə-nəm ]

La

A soft, malleable, silvery-white metallic element of the lanthanide series. It is used to make glass for lenses and lights for movie and television studios. Atomic number 57; atomic weight 138.91; melting point 920°C; boiling point 3,469°C; specific gravity 5.98 to 6.186; valence 3. See Periodic Table.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.