Puzzolan

Part of speech: noun

Definitions

1. A type of volcanic-derived ash that improves cement's structural integrity
2. A mineral additive derived from volcanic activity that enhances the properties of cement mixtures
3. A fine volcanic ash used to improve the strength and durability of concrete mixes

Etymology: The town of Pozzuoli, on the bay west of Naples, was known to the Romans as Puteoli, and its name is linked to a Latin verb meaning "to stink," probably a nod to the sulphurous vents and smells of the nearby volcanic ground. The ash found around that town was prized by Roman builders, who mixed it with lime to make a hydraulic mortar that hardened even underwater. Italians came to call such volcanic earth "pozzolana," literally "earth of Pozzuoli." The word then travelled into English as "puzzolan," an alternative spelling of "pozzolana." A town's name, a stinking verb, and a building material ended up linked in one term, and the material is still the reason concrete can cure in damp conditions.