A trough is a box-like drinking vessel for farm animals. Other senses of the word refer to things that are lower than their surroundings, like a trough:

• Trough (physics)
• Trough (meteorology);
• Trough (geology);
• a trough is also a noticeable and statistically recordable decline in an economy or graph.
• in chemistry it can be a Langmuir Blodgett Trough

See also trow.