The effect of the secondary vaporization of the liquid after it's been liquified from gas during the continuous decompression or cooling (or both). of gas condensation during the isothermal decompression.

The effect is counter-intuitive as most practical fluids experience decrease in density under isothermal decompressionThe term is misnomer as it actually means vaporization which is opposite to Condensation.

The most popular practical behavior of example of Retrograde Condensation behaviour is Natural Gas with initial temperature higher than pseudo-critical but lower than Cricondentherm.