Quaternities can be described as a group of four individuals or four elements that are related in some way. There are several synonyms for the word "quaternities", including foursome, quadruple, tetrad, and quartet. A foursome refers to a group of four people or things that are together in some way. Quadruple means fourfold or four times the amount of something. A tetrad is a set of four things that are similar or related. Finally, quartet refers to a group of four musicians who perform together. These synonyms can be used interchangeably with "quaternities" depending on the context and the intended meaning.