Main Entry: thal·li·um

Pronunciation: \ˈtha-lē-əm\

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