There are several synonyms for the word "pentatomic", which is used to describe a molecule or ion containing five atoms. Some common synonyms for pentatomic include pentaatomic, pentamerous, and quinquivalent. Other less commonly used synonyms include pentavalent, quinquivalent, and five-atomed. These words can be useful to use in place of pentatomic in scientific writing or when discussing molecules and ions with a specific number of atoms. Whether you're a chemist, biologist, physicist, or simply have an interest in science, it's important to have a wide range of scientific vocabulary at your disposal to be able to accurately describe complex concepts.