<unk>  is the ability of the lungs to stretch in a change in volume relative to an applied change in pressure. It is an important measurement in respiratory physiology.
It is the slope of the pressure-volume curve at a particular lung volume i.e. volume change per unit of pressure change (mL/cm H2O)
Normal value of<unk>  of intact lung = 200mLs/cmH2O 
.<unk>  is greatest at moderate lung volumes, and much lower at volumes which are very low or very high.
Pulmonary compliance
Airway resistance
Ventilation/perfusion ratio
Exercise capacity
Alveolar-arterial gradient
Cardiothoracic ratio
FEV1/FVC ratio
Diffusion capacity