Bookmaking is the practice of laying bets on various possible outcomes of a single event. It is a practice of betting by determining odds, and receiving and paying off bets on sports competitions such as horse racing and the like. The term originates from the practice of recording such wagers in a ledger or a 'book' and gives the term bookmaking for the practice of making the book.
The following is an example of state statute (Washington) defining the term.
Pursuant to [Rev. Code Wash. (ARCW) § 9.46.0213] "Bookmaking," as used in this chapter, means accepting bets, upon the outcome of future contingent events, as a business or in which the bettor is charged a fee or "vigorish" for the opportunity to place a bet.