The Collaborative International Dictionary of English v.0.48:
Fat \Fat\, n.
1. (Physiol. Chem.) An oily liquid or greasy substance making
up the main bulk of the adipose tissue of animals, and
widely distributed in the seeds of plants. See Adipose
tissue, under Adipose.
Note: Animal fats are composed mainly of three distinct fats,
tristearin, tripalmitin, and triolein, mixed in varying
proportions. As olein is liquid at ordinary
temperatures, while the other two fats are solid, it
follows that the consistency or hardness of fats
depends upon the relative proportion of the three
individual fats. During the life of an animal, the fat
is mainly in a liquid state in the fat cells, owing to
the solubility of the two solid fats in the more liquid
olein at the body temperature. Chemically, fats are
composed of fatty acid, as stearic, palmitic, oleic,
etc., united with glyceryl. In butter fat, olein and
palmitin predominate, mixed with another fat
characteristic of butter, butyrin. In the vegetable
kingdom many other fats or glycerides are to be found,
as myristin from nutmegs, a glyceride of lauric acid in
the fat of the bay tree, etc.
2. The best or richest productions; the best part; as, to
live on the fat of the land.
3. (Typog.) Work. containing much blank, or its equivalent,
and, therefore, profitable to the compositor.
Fat acid. (Chem.) See Sebacic acid, under Sebacic.
Fat series, Fatty series (Chem.), the series of the
paraffine hydrocarbons and their derivatives; the marsh
gas or methane series.
Natural fats (Chem.), the group of oily substances of
natural occurrence, as butter, lard, tallow, etc., as
distinguished from certain fatlike substance of artificial
production, as paraffin. Most natural fats are essentially
mixtures of triglycerides of fatty acids.