What is Adjusted Gross Income?

Legal Definition
In the United States income tax system, adjusted gross income (AGI) is an individual's total gross income minus specific deductions. Taxable income is adjusted gross income minus allowances for personal exemptions and itemized deductions. For most individual tax purposes, AGI is more relevant than gross income.

Gross income is sales price of goods or property, minus cost of the property sold, plus other income. It includes wages, interest, dividends, business income, rental income, and all other types of income. Adjusted gross income is gross income less deductions from a business or rental activity and 21 other specific items.

Several deductions (e.g. medical expenses and miscellaneous itemized deductions) are limited based on a percentage of AGI. Certain phase outs, including those of lower tax rates and itemized deductions, are based on levels of AGI. Many states base state income tax on AGI with certain deductions.

Adjusted gross income is calculated by subtracting Above-the-line deduction from gross income.
-- Wikipedia
Legal Definition
An individuals income before standard deductions have been subtracted, but after student loan interest payments have been subtracted.