from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Solid matter that is ejected into the air by an erupting volcano.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The solid material thrown into the air by a volcanic eruption that settles on the surrounding areas.
Greek tephrā, ash; see dhegwh- in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)
From the Ancient Greek τέφρα (tephra, "ash"). (Wiktionary)