(Science: chemistry, element) A rare metallic element. It occurs quite widely, but in small quantities, and always combined. It is isolated as a soft yellowish white metal, analogous to potassium in most of its properties.
Origin: NL, fr. L. Rubidus red, fr. Rubere to be red. So called from two dark red spectroscopic lines by means of which it was discovered in the lepidolite from Rozena, Moravia.