buckle up phrasal verbphr v FASTEN/DO UPto fasten your seat belt in a car, aircraft etc 系上安全带buckle up• Nancy got behind the wheel and buckled up.• The new law will require passengers in the rear seats of automobiles to buckle their seatbelts.• Eighty percent of motorists now buckle up, studies show.
→ buckle up at buckle1(2)