The term aggregate simply means the sum or the whole amount of something. When applied to different fields it can mean entirely different things. To avoid confusion, it is important to know the context, which is why the term is usually paired with another word and thus ends being an industry-specific technical term.
In economics, the terms using the word aggregate we most often hear are aggregate demand and supply. Aggregate demand is simply the total demand for goods and services during a specific period of time. On the other hand, aggregate supply refers to the total supply of goods produced during a specific period of time. Note that when considering aggregate supply it is important to consider not just the total production but also total import. The dynamics between aggregate demand and supply will determine pricing.
When it comes to accounting, there is also a thing called aggregate adjustment. It is used by lenders to describe how they determine the amount of money in a borrower’s escrow account to be paid back by the borrower at the closing of the loan. This is often used to ensure that borrowers maintain the proper amount in their escrow account until the loan is closed even after taxes and insurance has been deducted. While some lenders require this, some actually do not.