cossist

A practitioner of proto-algebra in Renaissance and Early Modern Europe.

The word "cossist" comes from the Italian cosa, meaning "thing." The cosa was the mystery that algebra was designed to solve -- it was the name given to the unknown quantity in an equation (our modern x).

So also were trained the Cossists and Rechenmeister of Germany in his tradition.

Pertaining to the cossists and their methods; cossic.

Clavius's treatise is, first of all, reckoned as one of the textbooks of cossist algebra.

Cossist algebra constituted essentially a sophisticated form of arithmetical problem-solving. Often it is difficult when reading a cossist text to discern where computational arithmetic leaves off and algebra begins.