In this chemical reaction, hydration plays an important role.

This area is rich in subterranean rivers, which serve as a source of groundwater.

He is receiving a basic living stipend.

Old Church Slavonic is the oldest recorded language of the Slavic group.

Old Church Slavonic is the first language written by the Slavs.

He was my student, but now he has become so proficient that it can be said 'the student has surpassed his teacher.'

Since he started his new job, he's been lively as if he were a fish back in water.

He absorbs new information like a sponge soaking up water.

The European water vole is a small mammal native to Europe.

This steam is what you see when water vapor cools down.