Real Dictionary

fat
a thick piece of soft material used to make something comfortable, give it shape, or protect it [...]
any of a class of naturally occurring soft greasy solids that are esters of glycerol and certain fatty acids. They are present in some plants and in the adipose tissue of animals, forming a reserve energy source, and are used in making soap and paint and
the giving of testimony on oath [...]
adjective: If you say that a person or animal is fat, you mean that they have a lot of flesh on their body and that they weigh too much. You usually use the word fat when you think that this is a bad thing.
uncountable noun: Fat is the extra flesh that animals and humans have under their skin, which is used to store energy and to help keep them warm.