Webster's Revised Unabridged Dictionary · 1913

Lavosium

Lavosium , noun

[New Latin, from Lavoisier, the celebrated French chemist.]

(Chemistry) A supposed new metallic element, which was said to have been discovered in pyrites, and some other minerals, and to be of a silver-white color, and malleable. It is not currently (1998) a recognized element.

Also: Lavoesium