Obs. Also cosse. [a. obs. F. cosse, ad. It. cosa thing, a translation of Arab. shai ‘thing,’ the term applied to the unknown quantity (or x) of an equation, etc.] In Rule of Coss, an early name for Algebra.
1570. Dee, Math. Pref., 6. That great Arithmeticall Arte of Æquation: commonly called the Rule of Coss, or Algebra.
1579. Digges, Stratiot., 55. This Art of Algebra or Rule of Cosse as the Italians terme it.
1706. Phillips (ed. Kersey), Cosse and Cossick, the old Word for Algebra.
1796. Hutton, Math. Dict., I. 335. Coss, Rule of, meant the same as Algebra, by which name it was for some time called, when first introduced into Europe through the Italians, who named it Regola de Cosa, the Rule of the thing; the unknown quantity, or that which was required in any question, being called cosa, the thing.
