toughen
verb uk/ˈtʌf.ən/ us/ˈtʌf.ən/
(MAKE STRONG)
[ T ]使坚韧；使变结实；加强
to make something or someone tough, strong, or stronger
The UN announced its intentions to toughen sanctions still further. 联合国宣布了要进一步加强制裁的意图。
The government wants to toughen (up) the existing drug laws/controls. 政府想要加强现有的有关毒品的法律／对毒品的控制措施。
His time in the army certainly toughened him up. 军旅生涯确实使他变得更加坚强。
Car windows are usually made from toughened glass. 汽车车窗通常是由钢化玻璃制成的。
(GET DIFFICULT)
[ I ]变困难
to become difficult to deal with
Amid toughening competition in the market, many firms are going out of business. 由于市场竞争愈趋激烈，许多公司只好歇业。