Merriam-Webster's Word of the Day for July 18, 2026, is quid pro quo. This term refers to something received or done in exchange for something given or done for another. It signifies an equivalent exchange or a reciprocal favor. For instance, if a favor is granted, a quid pro quo is typically expected in return. Negotiations often involve such exchanges, where one party agrees to a policy or action in return for something else. Historically, in the 1500s, quid pro quo referred to something obtained from an apothecary. Initially, it appeared in English to describe the substitution of one medicine for another. Over time, its meaning broadened to encompass more general equivalent exchanges. By the mid-1600s, it denoted a bargain where one thing was given for another. While not always unlawful, this concept frequently appears in legal contexts concerning less than legitimate exchanges.