Webster's Revised Unabridged Dictionary · 1913

Pinacone

Pinacone , noun

[From Greek {not transcribed}, {not transcribed}, a tablet. So called because it unites with water so as to form tablet-shaped crystals.]

(Chemistry) A white crystalline substance related to the glycols, and made from acetone; hence, by extension, any one of a series of substances of which pinacone proper is the type.