to reduce something by half or divide something into two equal pieces

In the past eight years, the elephant population in Africa has been halved. 在过去的8年中，非洲大象的数量减少了一半。

The potatoes will cook more quickly if you halve them before you put them in the oven. 如果把土豆切成两半再放进烤箱，它们会熟得更快。

If something halves, it is reduced by half.

Their profits have halved in the last six months. 在过去的6个月里，他们的利润减少了一半。