to mourn: to grieve a death or disaster, with the body and the land itself drooping in sorrow.
At its core this word is grief shown, not just felt. When a person does it, they tear their clothes, weep, refuse comfort, and put on the dark clothing of bereavement, the way Jacob does when he believes Joseph is dead. It covers grief for the dead, but also the heavy mourning a community takes on after a defeat, a plague, or the discovery that it has sinned against God.
The striking thing about this word is how easily it moves from people to the world around them. The prophets again and again say the land mourns, the pastures mourn, the vine and the fields mourn. This is not only poetry. In Hebrew the picture and the physical reality run together: a land in mourning is a land that has dried out, drooped, and lost its life, because mourning and withering look the same from the outside. So when Isaiah or Jeremiah says the earth mourns, the reader is meant to see both at once: the ground grieving and the ground going brown.
That double picture is why translators struggle. In the prophets the word can lean toward sorrow or toward drought, and often it deliberately means both. The senses below separate the plainly human grieving from the mourning of the natural world, but they are two faces of one word, not two unrelated words.