Engineering Design Precision Engineering
Precision engineering is tight tolerances with high repeatability 
Precision engineering is the ablity to be able to manufacture parts which have tight tolerances, but have high repeatability over time giving a 'reasonable' manufacturing process. Accuracy is (for manufacture) the ablity to produce a part to a quantifiable (highly controlled) value and the precision of that part is the ablity to repaet it time after time given the same external conditions. Precision implies accuracy and if often used for machine tools or optomechanical engineering, where the above example is of a parabolic reflecting mirror construted from interlocking hexagonal parts each having their 'part' of the mirror as the top surface. Production of optically correct lenses is usually given by a polynomial equation of nth degree, derived by optical engineers.