Deep″en (?), v. t. [imp. & p. p.Deepened (?); p. pr. & vb. n.Deepening.] 1. To make deep or deeper; to increase the depth of; to sink lower; as, to deepen a well or a channel.
It would... deepen the bed of the Tiber. Addison.
2. To make darker or more intense; to darken; as, the event deepened the prevailing gloom.
You must deepen your colors. Peacham.
3. To make more poignant or affecting; to increase in degree; as, to deepen grief or sorrow.
4. To make more grave or low in tone; as, to deepen the tones of an organ.
Deepens the murmur of the falling floods. Pope.