trough
/ˈtrɒf/noun
1- a long, narrow open container for animals to eat or drink out of（给动物进食或饮水的）槽：
a water trough.
水槽。
1.1
- a container of a similar shape used for a purpose such as growing plants or mixing chemicals（用于培植植物、调配化学制品的）槽形容器。
1.2
- a channel used to convey a liquid（运水的）沟槽。
1.3
- a long hollow in the earth's surface地表槽谷：
a vast glacial trough.
巨大的冰槽。
1.4
- an elongated region of low barometric pressure低压槽, 槽形低压。
1.5
- a hollow between two wave crests in the sea（海水水波之间的）波谷。
1.6
- a low level of economic activity（经济周期中的）低谷期。
1.7
- Mathematics a region around the minimum on a curve of variation of a quantity【数】凹点。
1.8
- a point of low achievement or satisfaction低谷（成绩小或不令人满意）：
learning a language is a series of peaks and troughs.
语言学习过程中会有一系列的高峰期和低谷期。
词源
Old English trog, of Germanic origin; related to Dutch trog and German Trog, also to TREE.