from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A soft, bright, silvery rare-earth element occurring in two allotropic forms and used as an x-ray source for portable irradiation devices, in some laser materials, and in some special alloys. Atomic number 70; atomic weight 173.04; melting point 824°C; boiling point 1,196°C; specific gravity 6.972 or 6.54 (25°C) depending on allotropic form; valence 2, 3. See Table at element.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A metallic chemical element (symbol Yb) with an atomic number of 70.

from the GNU version of the Collaborative International Dictionary of English

  • n. A rare element of the boron group, sometimes associated with yttrium or other related elements, as in euxenite and gadolinite. Symbol Yb; provisional atomic weight 173.2. Cf. yttrium.

from The Century Dictionary and Cyclopedia

  • n. In making the ‘glowers’ or filaments for the Nernst incandescent electric lamps it has been found that the mixture of zirconia with the earths of the yttria group gives the most satisfactory results when the latter contain a large proportion of ytterbium as compared with yttrium.
  • n. Chemical symbol, Yb; atomic weight, 173 (?). An element discovered by Marignac in gadolinite, in regard to which little is known.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a soft silvery metallic element; a rare earth of the lanthanide series; it occurs in gadolinite and monazite and xenotime


After Ytterby, a town in Sweden.
(American Heritage® Dictionary of the English Language, Fourth Edition)
Named for the Swedish town of Ytterby. (Wiktionary)



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