1. harden off : 使受冷而变得耐寒；
及物动词
不及物动词
1. （使）变硬;（使）硬化
When something hardens or when you harden it, it becomes stiff or firm.
2. （使）（态度、想法）变得更坚定;（使）变得更强硬
When an attitude or opinion hardens or is hardened, it becomes harsher, stronger, or fixed.
1. cause to accept or become hardened to
habituate
e.g. He was inured to the cold
2. make fit
e.g. This trip will season even the hardiest traveller
Synonym: season
3. harden by reheating and cooling in oil
e.g. temper steel
Synonym: temper
4. become hard or harder
e.g. The wax hardened
Synonym: indurate
5. make hard or harder
e.g. The cold hardened the butter
Synonym: indurate