from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A soft silvery-white metallic element of the alkali group that ignites spontaneously in air and reacts violently with water, used in photocells and in the manufacture of vacuum tubes. Atomic number 37; atomic weight 85.47; melting point 38.89°C; boiling point 688°C; specific gravity (solid) 1.532; valence 1, 2, 3, 4. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A metallic chemical element (symbol Rb) with an atomic number of 37.
from the GNU version of the Collaborative International Dictionary of English
- n. A rare metallic element of the alkali metal series, atomic number 37. It occurs quite widely, but in small quantities, and always combined. It is isolated as a soft yellowish white metal, analogous to potassium in most of its properties. Symbol Rb. Atomic weight, 85.48.
from The Century Dictionary and Cyclopedia
- n. Chemical symbol, Rb; atomic weight, 85.25. A metal belonging to the group of elements which includes lithium, sodium, potassium, and cæsium: so named from the reddish tint of its salts.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a soft silvery metallic element of the alkali metal group; burns in air and reacts violently in water; occurs in carnallite and lepidolite and pollucite
From Latin rūbidus, red; see reudh- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
A New Latin word derived by German chemist R. W. Bunsen in 1861, from Latin rubidus ("red") because its spectrum has two red lines. (Wiktionary)