You're absolutely right, I don't know why I had attributed the name to the full duplex nature. And of course, there is also USART, where you can have a separate

You're absolutely right, I don't know why I had attributed the name to the full duplex nature. And of course, there is also USART, where you can have a separate clock line, which allows you to omit the start and stop bits too. At that point, you're essentially turning your UART into a single connection SPI bus.