There are several synonyms that can be used in place of the term "calendar year". One could use the phrase "fiscal year" instead, which refers to a 12-month period used for financial reporting purposes. Another option is "tax year", which is the 12-month period used for calculating and reporting taxes. "Anniversary year" can also be used as a similar term, referring to the annual celebration of a particular event or milestone. Additionally, "annual period" and "yearly cycle" are other phrases that can be used in place of "calendar year". Each of these synonyms provides a slightly different context or emphasis for understanding the passage of a year.