·vi To become deeper; as, the water deepens at every cast of the lead; the plot deepens.
II. Deepen ·vt To make more poignant or affecting; to increase in degree; as, to deepen grief or sorrow.
III. Deepen ·vt To make more grave or low in tone; as, to deepen the tones of an Organ.
IV. Deepen ·vt To make deep or deeper; to increase the depth of; to sink lower; as, to deepen a well or a channel.
V. Deepen ·vt To make darker or more intense; to Darken; as, the event deepened the prevailing gloom.