deepen
verbUK /ˈdiːpən/
US /ˈdiːpən/
To make something go down further or become deeper.
The workers had to deepen the pool so it would be safe for diving.
OTHER MEANINGS
2. To become stronger or more serious.
Their friendship deepened over the years.
3. To make a color darker or more intense.
The sunset deepened the sky to a rich orange.
4. To make a sound lower in pitch.
He deepened his voice to sound more serious.
5. To gain a better understanding of something.
Reading the book deepened her knowledge of history.