Lanthanum

• POS: Noun
• HYPHEN: lan=tha=num

CIDE DICTIONARY

Lanthanum, n. [NL., fr. Gr. lanqa`nein to lie hid, to be concealed.].

 A rare element of the rare earth group of the metals, of atomic number 57, allied to aluminum. It occurs in certain rare minerals, as cerite, gadolinite, orthite, etc., and was so named from the difficulty of separating it from cerium, didymium, and other rare earth elements with which it is usually associated. Atomic weight 138.9. Symbol La.  [1913 Webster]

OXFORD DICTIONARY

Lanthanum, n. Chem. a silvery metallic element of the lanthanide series which occurs naturally and is used in the manufacture of alloys.

Usage

Symb.: La.

Etymology

Gk lanthano escape notice, from having remained undetected in cerium oxide