Why are lipids not considered polymers?

Hint: Biopolymers are natural polymers made by living organisms' cells. Monomeric units are covalently bound to generate bigger molecules in biopolymers. Polynucleotides, polypeptides, and polysaccharides are the three primary groups of biopolymers, which are categorised based on the monomers employed and the structure of the biopolymer generated. Long polymers made up of 13 or more nucleotide monomers, such as RNA and DNA, are known as polynucleotides. Polypeptides and proteins are polymers of amino acids. Polysaccharides are linear or branched polymeric carbohydrates.

Complete answer:
Polymers are interconnected sequences of smaller molecules, whereas lipids start with a single molecule, such as a fatty acid, and create long chains by a chemical reaction, such as dehydration. Dehydration is the process of combining two molecules to form a new, larger one by extracting one hydrogen from one and an OH from the other, resulting in one molecule of free water.
Lipids aren't polymers since they lack a monomer unit.
Simply put, lipids are a type of fat having a glycerol molecule and a two or three fatty acid chain.
Although there is always one glycerol, the number of fatty acids varies.
As a result, there isn't a monomer unit.
A polymer also has no natural set size, thus it must be terminated by a process in living organisms. Additional hydrocarbons may not spontaneously dehydrate at the open end, hence some lipids have a natural limit. Cholesterol is an example of a lipid.

Note:
Lipids are hydrocarbon-containing compounds that are essential to the structure and function of living cells. Lipids include fats, oils, waxes, certain vitamins (such as A, D, E, and K), hormones, and the non-protein portion of the cell membrane.