In British English, both "taxi" and "cab" are used interchangeably and are perfectly understood, though they carry slightly different cultural weights. "Taxi" is the more formal and standard term used in official contexts and signage. "Cab" is very common in casual speech, particularly in London, where the iconic vehicles are almost always referred to as "Black Cabs." Historically, "cab" is short for cabriolet, a type of horse-drawn carriage, while "taxi" comes from taximeter. In 2026, you will frequently hear Londoners say they are "grabbing a cab" or "calling a taxi." However, there is a technical distinction in the UK: a "taxi" (like a Black Cab) can be hailed on the street, whereas a "Private Hire Vehicle" (like an Uber or a minicab) must be pre-booked and is technically not a "taxi" in the eyes of the law, though most people will still casually call them "cabs."