cossist

English

Etymology

From Italian cossista, from the word cosa (“thing”), in reference to an unknown quantity to be determined + -ista. See rule of coss.

Noun

cossist (plural cossists)

1. (historical) A practitioner of proto-algebra in Renaissance and Early Modern Europe.
   • 2005, Amir D. Aczel, Descartes' Secret Notebook: A True Tale of Mathematics, page 121:

     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).

   • 2014, L. E. Sigler, Leonardo Pisano (Fibonacci): The Book of Squares, page xvii:

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

Adjective

cossist (not comparable)

1. Pertaining to the cossists and their methods; cossic.
   • 1989, Chikara Sasaki, Descartes's Mathematical Thought, page 90:

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

   • 2018, Michael Sean Mahoney, The Mathematical Career of Pierre de Fermat, 1601-1665), page 5:

     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.