Definify.com
Webster 1913 Edition
Fat
1. 
A large tub, cistern, or vessel; a vat. 
[Obs.] 
The 
fats 
shall overflow with wine and oil. Joel ii. 24.
2. 
A measure of quantity, differing for different commodities. 
[Obs.] 
Hebert.
 Fat
,Adj.
 [
Com
par.
 Fatter
; sup
erl.
 Fattest
.] [AS. 
fǣtt
; akin to D. vet
, G. fett
, feist
, Icel. feitr
, Sw. fet
, Dan. fed
, and perh. to Gr. πῖδαξ 
spring, fountain, πιδύειν 
to gush forth, πίων 
fat, Skr. pi 
to swell.] 1. 
Abounding with fat
; as: (a) 
Fleshy; characterized by fatness; plump; corpulent; not lean; 
as, a 
. fat 
man; a fat 
ox(b) 
Oily; greasy; unctuous; rich; – said of food. 
2. 
Exhibiting the qualities of a fat animal; coarse; heavy; gross; dull; stupid. 
Making our western wits 
fat 
and mean. Emerson.
Make the heart of this people 
fat
. Is. vi. 10.
3. 
Fertile; productive; 
as, a 
 fat 
soil; a fat 
pasture.4. 
Rich; producing a large income; desirable; 
as, a 
 fat 
benefice; a fat 
office; a fat 
job.Now parson of Troston, a 
fat 
living in Suffolk. Carlyle.
5. 
Abounding in riches; affluent; fortunate. 
[Obs.] 
Persons grown 
fat 
and wealthy by long impostures. Swift.
6. 
(Typog.) 
Of a character which enables the compositor to make large wages; – said of matter containing blank, cuts, or many leads, etc.; 
as, a 
 fat 
take; a fat 
page.Fat lute
, a mixture of pipe clay and oil for filling joints.
 Fat
,Noun.
 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
. ☞ 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 land3. 
(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.
 Fat
,Verb.
 I.
 To grow fat, plump, and fleshy. 
An old ox 
fats 
as well, and is as good, as a young one. Mortimer.
Webster 1828 Edition
Fat
FAT
,Adj.
  1.
  Fleshy; plump; corpulent; abounding with an oily concrete substance, as an animal body; the contrary to lean; as a fat man; a fat ox.2.
  Coarse; gross.Nay, added fat pollutions of our own.
3.
  Dull; heavy; stupid; unteachable.Make the heart of this people fat.  Is. 6.
4.
  Rich; wealthy; affluent.These are terrible alarms to persons grown fat and wealthy.
5.
  Rich; producing a large income; as a fat benefice.6.
  Rich; fertile; as a fat soil; or rich; nourishing; as fat pasture.7.
  Abounding in spiritual grace and comfort.They [the righteous] shall be fat and flourishing.  Ps. 42.
FAT
,Noun.
  1.
  An oily concrete substance, deposited in the cells of the adipose or cellular membrane of animal bodies.  In most parts of the body, the fat lies immediately under the skin.  Fat is of various degrees of consistence, as in tallow, lard and oil.  It has been recently ascertained to consist of two substances, stearine and elaine, the former of which is solid, the latter liquid, at common temperatures, and on the different proportions of which its degree of consistence depends.2.
  The best or richest part of a thing.Abel brought of the fat of his flock.  Gen 4.
FAT
,Verb.
T.
  FAT
,Verb.
I.
  An old ox fats as well, and is as good, as a young one.