The antonyms for the term "synthetic resins" include "natural resins" and "organic compounds." In contrast to synthetic resins, natural resins are derived from plant secretions and have been used for thousands of years as adhesives, coatings, and varnishes. Examples of natural resins include gum arabic, rosin, and shellac. Organic compounds, on the other hand, are carbon-based compounds found in nature that have a wide range of applications, including as solvents, plastics, and pharmaceuticals. Examples of organic compounds include ethanol, propane, and methane. By understanding these antonyms, one can gain a broader understanding of the various types of materials and substances used in industry and manufacturing.