n.
Pronunciation: ' tha-l ē - ə m
Function: noun
Etymology: New Latin, from Greek thallos green shoot; from the bright green line in its spectrum
Date: 1861
: a soft poisonous metallic element that resembles lead in physical properties, occurs sparsely in a number of common ores, and is used chiefly in the form of compounds especially in photosensitive devices and formerly as a pesticide ― see ELEMENT table