Atramentum

Atramentum or atrament, generally means a very black, usually liquid, substance. For example, an octopus may emit a puff of atrament (see cephalopod ink).

In ancient Rome, the term atramentum signified any black colouring substance used for any purpose. The Romans distinguished three principal kinds of atramentum, one called librarium (or scriptorium), another called sutorium, the third tectorium.