The word "oxylium" is a scientific term used to describe a type of compound containing a positively charged oxygen ion. When looking for synonyms, it's important to consider the context in which the word is being used. Possible alternatives include "oxidonium," "oxacation," "oxonium," or "oxonium ion." These terms specifically refer to a type of cation that contains oxygen, and may be used interchangeably depending on the scientific field and context. Other related terms may include "protonated oxygen," "oxygen ion," or "hydronium," which all describe different aspects of this type of compound.