boot
n.— «The regulation requires all businesses that use shopping carts to submit an “abandoned cart prevention plan” to the city. Solutions could range from hiring parking lot attendants to installing devices that prevent carts from leaving a store. The latter, known as Electronic Theft Deterrent Systems, are an increasingly popular option locally. The ETDS is more commonly known as a “boot” and relies on a radio-frequency-controlled wheel lock that triggers when a cart strays too far from a store.» —“Shopping Cart Crackdown” by Serdar Tumgoren Gilroy Dispatch (California) Apr. 4, 2007. (source: Double-Tongued Dictionary)