The pieze is the unit of pressure in the metre-tonne-second system of units (mts system), used, e. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface The metre-tonne-second or mts system of units is a system of Physical units It was invented in France hence the unit names sthène and pièze g. , in the former Soviet Union 1933-1955. It is defined as one sthene per square metre. The sthène is the unit of force in the Metre-tonne-second system of units (mts invented in France and used in the Soviet Union 1933 - 1955. M^2 redirects here For other uses see M². CM2 redirects here The symbol is pz.