Also found in: Thesaurus, Medical, Financial, Acronyms, Encyclopedia, Wikipedia.
Related to lanthanum: Lanthanum oxide, Lanthanum carbonate
n. Symbol La
A soft, silvery-white, malleable, ductile element of the lanthanide series, obtained chiefly from the minerals monazite and bastnaesite and used in glass manufacture and with other rare-earth elements in carbon lights for movie and television studio lighting. Atomic number 57; atomic weight 138.91; melting point 920°C; boiling point 3,464°C; specific gravity 6.145 (at 25°C); valence 2, 3. See Periodic Table.
[New Latin, from Greek lanthanein, to escape notice (from the finding of the element hidden in oxide of cerium).]
(Elements & Compounds) 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
[C19: New Latin, from Greek lanthanein to lie unseen]
lan•tha•num(ˈlæn θə nəm)
a rare-earth, trivalent, metallic element, allied to aluminum, found in certain minerals, as monazite. Symbol: La; at. wt.: 138.91; at. no.: 57; sp. gr.: 6.15 at 20°C.
[< New Latin (1841) < Greek lanthán(ein) to escape notice + New Latin -um, for -ium -ium2]
Symbol La A soft, easily shaped, 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. See Periodic Table.
Switch to new thesaurus
|Noun||1.||lanthanum - a white soft metallic element that tarnishes readily; occurs in rare earth minerals and is usually classified as a rare earth|