Extend vs Deepen - What's the difference?

In intransitive terms the difference between extend and deepen

is that extend is to possess a certain extent while deepen is to become lower in tone.

(en verb)

To increase in extent.

To possess a certain extent.

To cause to increase in extent.

To cause to last for a longer period of time.

To straighten (a limb).

To bestow; to offer; to impart; to apply.

to extend sympathy to the suffering

To increase in quantity by weakening or adulterating additions.

to extend liquors

(UK, legal) To value, as lands taken by a writ of extent in satisfaction of a debt; to assign by writ of extent.

* enlarge * expand * increase * lengthen * stretch * widen

* extendible (adjective) * extensible (adjective) * extensive (adjective) * extension * extent

(en verb)

To make deep or deeper

They deepened the well by 200 feet.

To make darker or more intense; to darken

The event deepened the prevailing gloom.

To make more poignant or affecting; to increase in degree

News of her death deepened my sorrow.

To make lower in tone

The tuner deepened the tone of the organ.

To become deeper

The water deepens as you go toward the middle of the channel.

To become darker or more intense

The crisis deepened in the following weeks.

To become lower in tone

His voice deepened with age.

(defn)

* English ergative verbs