Definitions

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

  • n. An extremely unstable radioactive element of the alkali metals, produced artificially from actinium or thorium, having approximately 19 isotopes, the most stable of which is Fr 223 with a half-life of 21 minutes. Atomic number 87; valence 1. See Table at element.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A metallic chemical element (symbol Fr) with an atomic number of 87.

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

  • n. a radioactive element of the alkali-metal group discovered as a disintegration product of actinium

Etymologies

After France .
(American Heritage® Dictionary of the English Language, Fourth Edition)
From French francium, from France +‎ -ium (after the native country of Marguerite Perey). (Wiktionary)

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