a window: an opening cut through a wall to let in light and air and to see or pass through
At ground level the word simply names a window, an opening bored through the wall of a house, a city wall, the ark, or the temple. The root behind it means to pierce or hollow out, so the word pictures a hole cut through solid wall rather than a modern glass pane. In the ancient world such an opening was either left open or filled with a wooden lattice.
The uses fall into two shades. Most windows in the Bible are ordinary and operable: you open them, lean out of them, lower a person through them, or watch through them. A smaller group belongs to sacred and royal building, where the word names the fixed, recessed, lattice-filled windows of the temple, built to admit light without letting anyone see in or climb through.
For so plain a word, the window carries surprising narrative weight. It is where people are rescued (Noah releases the raven, Rahab lowers the spies, Michal saves David, Elisha shoots the arrow of victory), and it is where danger arrives (invaders climb in, death itself is pictured climbing through the windows, and Jezebel is thrown down from one). It is also the frame for a recurring scene in which a woman watches from a window as a dynasty falls: Sisera's mother, Michal, and Jezebel each appear this way.