Total parenteral nutrition (TPN): 

An intravenous solution made up of two major components, lipids and hyperalimentation, used to provide nutrition to infants who cannot completely rely on their intestines for digesting and absorbing food.

Lipid:

The part of TPN that provides fats

Hyperalimentation (HAL): 

The part of TPN that provides sugar, protein, electrolytes and other important components of nutrition, such as vitamins and elements. 

Formula: 

A non-human milk product made to provide nutrition to an infant.  There are many compositions, with different amounts of protein, fat, carbohydrate and total calories, to provide for a wide variety of problems in the neonate. 

Fortifier: 

a supplement often added to breast milk that is fed to premature infants to maximize intake of calories, calcium and phosphorous, among other things.

Medium chain triglyceride (MCT) oil: 

a fat supplement given to boost the amount of calories an infant receives.