terra sigillata

noun3

1. •
   A type of fine, red Roman pottery made from the first to the third centuries AD in Gaul.
2. •
   A type of fine clay slip produced by mixing clay-water mixture with deflocculant and decanting the resulting water.

   • Terra sigillata, or ‘terra sig’ for short, is made by mixing a suitable clay with water and a deflocculant and leaving it to stand until the heavier particles of clay settle out. — 2024
3. •
   A type of astringent earth or clay originally from the Greek islands, formerly used as a medicine and antidote.

   • Terra sigillata (sealed earth) was a greasy clay, containing silica, alumina, chalk, magnesia and oxide of iron, found on the Greek islands of Lemnos, Melos and Samos. — 1997