from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A volcanic rock formed by the welding together of tuff material from an explosive volcanic eruption.
Latin ignis, fire + imber, imbr-, rain + -ite1.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin ignis ("fire") + imbris ("shower; stormcloud") + -ite. (Wiktionary)