adjective
Definition: Describing a type of compound that includes complex cations, often with names that end in '-onium'.
Example: The chemist studied an onium compound to understand its properties better.
noun
Definition: A type of cation formed by adding a proton to the hydride of certain elements, such as those in the nitrogen, chalcogen, or halogen groups.
Example: The chemist studied the properties of various onium compounds in the lab.