Aperture is a noun that refers to an opening or a gap.

The latin word aperire (app er EYE ray) means ‘to open.’ From there, we get our word of the day which holds on to a meaning very close to its origin. Here’s an example of aperture in use:

As a kid I was curious about what would happen if I stuck my head in the aperture between walls in the attic. I learned a valuable lesson that day. Some openings are better off staying closed.