Learn how to say Thallium correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word thallium:
the chemical element of atomic number 81, a soft silvery-white metal which occurs naturally in small amounts in iron pyrites, sphalerite, and other ores. Its compounds are very poisonous. (Symbol: Tl)
mid 19th century: modern Latin, from Greek thallos ‘green shoot’, because of the green line in its spectrum