Joint returns refer to filing taxes jointly with one's spouse or partner. However, there are alternative words and phrases that can substitute for joint returns. Firstly, 'married filing jointly' is a commonly used synonym as it clearly indicates that both individuals are married and filing taxes together. Another similar phrase is 'joint income tax returns' which emphasizes that the tax return is filed jointly, rather than separately. Additionally, 'joint tax return' or 'married joint filer' can be used to refer to the same thing. Lastly, 'combined tax return' is another synonym that emphasizes the combining of incomes and deductions for a joint filing.