Origin

The character 窒 combines a window or opening (穴, the hole radical at top) with a component 至 that hints at pronunciation. The idea is that something blocks or fills up an opening—plugging it, making it obstructed. The bottom component 至 tells you roughly how to say the character, not what it means. Over time, this visual idea of a hole being stopped up came to mean "plug up" or "obstruct" more generally.