Word Study
thallium
WORDNET DICTIONARY
Noun thallium has 1 sense
- thallium(n = noun.substance) atomic number 81, tl - a soft grey malleable metallic element that resembles tin but discolors on exposure to air; it is highly toxic and is used in rodent and insect poisons; occurs in zinc blende and some iron ores; Array is a kind of metal, metallic element
CIDE DICTIONARY
thallium, n. [NL., fr. Gr. young or green shoot or branch, twig. So called from a characteristic bright green line in its spectrum.].
A rare metallic element of the aluminium group found in some minerals, as certain pyrites, and also in the lead-chamber deposit in the manufacture of sulphuric acid. It is isolated as a heavy, soft, bluish white metal, easily oxidized in moist air, but preserved by keeping under water. Symbol Tl. Atomic weight 203.7. [1913 Webster]
OXFORD DICTIONARY
thallium, n. Chem. a rare soft white metallic element, occurring naturally in zinc blende and some iron ores.
Derivative
thallic adj. thallous adj.
Etymology
formed as THALLUS, from the green line in its spectrum
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