Isochronously is defined as something that is done with equal time intervals or at the same rate. There are a few synonyms for this word, including synchronously, in unison, simultaneously, and uniformly. Synchronously refers to something that occurs at the same time or in a coordinated manner. In unison also describes a group or action that is done together at the same time. Simultaneously describes two or more things that happen at the same time. Uniformly refers to a steady and even pace or behavior. These synonyms can be used interchangeably with isochronously depending on the context of the sentence.