To transact means to carry out or complete a piece of business. When you transact something, you're conducting an exchange or making a deal happen. If you buy a book at a bookstore, you're transacting: money changes hands, you get your book, and the store gets paid.

Banks transact millions of dollars every day, moving money between accounts and processing payments. A real estate agent helps people transact the sale of a house, handling all the paperwork and negotiations needed to complete the deal. Even something as simple as trading baseball cards with a friend involves transacting, though we usually save the word for more formal or important exchanges.

The word comes from business and legal contexts, which is why it sounds more serious than just saying “do business” or “make a deal.” When lawyers say that parties transacted an agreement, they mean the deal was properly completed and legally binding. You might hear someone say “let's transact this quickly” when they want to finish a business matter efficiently.

A transaction is the noun form: each purchase you make is a transaction, and your bank statement lists all your transactions for the month. While you probably won't use transact as often in casual conversation, understanding it helps you recognize when serious business is being conducted rather than just discussed.