What term refers to a larger substance made of simpler substances?

The term that refers to a larger substance made of simpler substances is "polymer." Polymers are large molecules made up of repeating structural units, known as monomers, which are smaller and simpler. This concept is fundamental in various biological and chemical contexts, where complex molecules are formed through the process of polymerization, where monomers are chemically bonded together.

For example, in biology, proteins, nucleic acids, and carbohydrates are all types of polymers that serve critical functions within living organisms. In contrast, the term "monomer" specifically describes those smaller units that join together to form a polymer. While carbohydrates and peptides are specific types of polymers, they do not encompass the broader definition of what a polymer is. Thus, the most accurate answer is the term "polymer," as it captures the essence of larger substances being composed of simpler units.