Mesomerism is a term used in organic chemistry to describe the condition of chemical compounds that are intermediate in nature, i.e., having some properties of both its resonance structures. There are several synonyms for mesomerism, including resonance, delocalization, and conjugation. Resonance refers to the phenomenon where the electrons in a molecule move back and forth between alternative structures. Delocalization is the movement of electrons that are not localized in a specific atom or bond. Conjugation refers to the extension of pi-orbitals over a series of adjacent atoms, resulting in resonance stabilization. All these synonyms describe the same chemical concept of mesomerism, which is essential for understanding the physical and chemical properties of many organic compounds.