A bobby is a British nickname for a police officer, like how Americans might say “cop.” The word comes from Sir Robert Peel, who founded London's Metropolitan Police in 1829. Since “Bobby” is a common nickname for Robert, people started calling police officers bobbies in his honor.

In old British stories and movies, you might see a bobby walking the streets of London in a distinctive tall helmet, helping citizens and keeping order. The word has a friendly, almost affectionate tone. While it's less common today, you'll still hear it used, especially in historical contexts or when someone wants to evoke that traditional image of British policing.