The phrase "once quarter" refers to a quarter of a year or three months. However, there are several synonyms for this phrase that can be used interchangeably depending on the context. These include "every three months," "quarterly," "every quarter," and "four times a year." Some other phrases that convey the same meaning are "every quarter year," "every fiscal quarter," and "every 90 days." Whether you are discussing financial or business matters, scheduling events or appointments, or planning personal objectives, using these synonyms for "once quarter" can add variety and clarity to your communication.