thorium

thorium is defined in Webster's Unabridged Dictionary (1913) with 1 sense. The full text of each entry is reproduced verbatim below.

Definitions

  1. 1.A metallic element found in certain rare minerals, as thorite, pyrochlore, monazite, etc., and isolated as an infusible gray metallic powder which burns in the air and forms thoria; -- formerly called also thorinum. Symbol Th. Atomic weight 232.0.

Source: Webster's Unabridged Dictionary, 1913 edition (public domain, via GCIDE / Project Gutenberg).

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