What does accuracy mean?
The definition of accuracy
Ac”cu*ra*cy (#; 277), n.
Etym: [See Accurate.]

The state of being accurate; freedom from mistakes, this exemption arising from carefulness; exact conformity to truth, or to a rule or model; precision; exactness; nicety; correctness; as, the value of testimony depends on its accuracy. The professed end [of logic] is to teach men to think, to judge, and to reason, with precision and accuracy. Reid. The accuracy with which the piston fits the sides. Lardner.