trass

1. A white to grey volcanic tufa, formed of decomposed trachytic cinders, sometimes used as a cement.
2. A coarse sort of plaster or mortar, durable in water, and used to line cisterns and other reservoirs of water.

Pronounced as (IPA)

/tɹɑːs/

Etymology

From Dutch tras or German Trass, probably from Italian terrazzo (“terrace”). See terrace.

Synonyms

ash

volcanic ash

pozzolan

pozzolana

tephros