to burn the skin with boiling liquid or steam

I dropped a pan of boiling water and scalded my leg. 我一锅沸水没端住，把腿烫伤了。

to put something in boiling water or steam in order to make it completely clean

Scald the needles to sterilize them. 烫洗针头进行消毒。

to heat a liquid until it almost boils

Scald the milk and then add it to the egg and sugar mixture. 把牛奶煮至将沸，然后倒入鸡蛋白糖的混合物中。

an injury to the skin caused by boiling liquid or steam