jack sth ↔ up phr v [T] 1 to lift something heavy using a jack 〔用起重器〕顶［托］起〔重物〕: Dad jacked the car up so I could change the tyre. 爸爸用起重器托高汽车让我换轮胎。 2 to increase prices, sales etc by a large amount 大幅度提高〔价格、销量等〕: Airlines always jack up fares at Christmas. 航空公司总是在圣诞节大抬票价。