the world: the whole habitable, fruitful earth, seen as the ordered realm God founded and the peopled stage of human life
This is a poetic word for the world, and it turns up almost only in poetry (the Psalms, Isaiah, Job, a few others). It almost always stands beside the ordinary word for earth or land in the balanced lines of Hebrew verse, and it adds a shade that plain "earth" does not carry. Where the common word can mean dirt, ground, territory, or a country, this word pictures the earth as the inhabited, productive world: the fruitful, peopled globe as a single whole.
That one picture is looked at from two angles. Sometimes the focus is the world as God made it and holds it steady: its foundations, the moment he formed it, the way he set it firm so it cannot be shaken. Sometimes the focus is the world as it is now full of life: its inhabitants, the nations, the place where God reigns and which he will judge. These are not two different worlds but two views of the same one.
One word carries both because, for these poets, the world cannot be separated from the God who founded it or the people who fill it. To name it is to call up the whole living, ordered earth at once, which is exactly why it so often appears in the phrase "the world and all who live in it."