Deepen

1. v. i. To become deeper; as, the water deepens at every cast of the lead; the plot deepens.
2. v. t. To make deep or deeper; to increase the depth of; to sink lower; as, to deepen a well or a channel.
3. v. t. To make darker or more intense; to darken; as, the event deepened the prevailing gloom.
4. v. t. To make more poignant or affecting; to increase in degree; as, to deepen grief or sorrow.
5. v. t. To make more grave or low in tone; as, to deepen the tones of an organ.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.