the fact of costing a lot of money, especially more than you want to pay synonym expense花钱多的;昂贵的;价钱高的 the costliness of training new employees 培训新员工的成本
the fact of causing problems or the loss of something synonym expense引起困难的;造成损失的 war's terrible costliness (= lots of people can die and be injured) 战争的巨大代价