molecular distillation noun
: distillation that is carried out under a high vacuum in an apparatus so designed as to permit molecules escaping from the warm liquid to reach the cooled surface of the condenser before colliding with other molecules and consequently returning to the liquid and that is used in the purification of substances of low volatility (as in the separation of vitamin A and vitamin E from fish-liver oils)
Seen & Heard
What made you want to look up molecular distillation? Please tell us where you read or heard it (including the quote, if possible).